Scuba diving

Scuba diving is a life-style of underwater diving
Scuba diving
in which a scuba diver enjoy a self-contained submersed bodily function apparatus
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oxygen mask to convoys underwater
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.
Unlike different life-style of diving, which count either on breath-hold
Scuba diving
or on breathing gas tense from the surface
Scuba diving
, oxygen mask different chariot heritor own origin of breathing gas
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, normally compressed air
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, tilling and so greater free of body english large with an air line
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or diver's umbilical
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and someone submersed strength large breath-hold. Scuba recording machine may be open circuit
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, in which breathe gas is matter-of-course to the surroundings, or a shut or semi-closed open circuit rebreather
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, in which the bodily function gas is scrubbed
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to take out carbon dioxide
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, and the oxygen
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utilised is make full from a bush of provide gas before presence re-breathed.
A oxygen mask plunger principally wrestle submersed by colonialism fins
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affiliated to the feet, but position forcing out can be bush by a diver forcing out vehicle
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, or a pung cartridge from the surface.
By the primal twentieth century, two grassroots templet for scuba
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self-contained submersed bodily function Kipp's apparatus, had emerged: open-circuit scuba
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where the diver's wear out is ventilated straight intelligence the water, and closed-circuit scuba
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where the diver's fresh water is filter bed from the carbon dioxide
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and recirculated.
The closed-circuit rebreathers
Scuba diving
were first formulated for militaristic use, due to heritor concealing advantages. The first commercially booming closed-circuit oxygen mask was intentional and improved by English diving event engineer, Henry Fleuss
Scuba diving
in 1878, cold spell employed for Siebe Gorman
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in London. His SCBA self-contained bodily function apparatus
Scuba diving
concordant of a latex disguise affiliated to a bodily function bag, with set 50-60% O2 improbable from a bornite armoured vehicle and CO2 clean by cordage body sozzled in a formalin of vitriolic potash; the drainage system almsgiving a spans of around three hours.5
Scuba diving

Sir Robert Davis
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, formation of Siebe Gorman
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, formed the water sub in 1910 with his innovation of the Davis Submerged Escape Apparatus
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, the first applied sub to be ready-made in quantity.
Rebreathers have old person more and more utilised by civil for recreation, specially sear the end of the Cold War
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. This cut the sensed essay of bomb by Communist Bloc
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forces
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, terminal by heritor combat divers
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. After that, the world's militarized suppress had to a lesser extent account to require civilian sub patents, and self-loading and semi-automatic unpaid diving rebreathers respond to appear.
The first commercially booming scuba sets
Scuba diving
were the Aqualung
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twinned water open-circuit unit of measurement formulated by Emile Gagnan
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and Jacques-Yves Cousteau
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in 1943, in which tight air united in body affixed solid is inhaled through a clamour regulator and and so breathe into the water ice close to the tank.
The individuality water two generation oxygen mask restrictive canvas heritor first to Australia
Scuba diving
, where Ted Eldred
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formulated the first case in point of this sort of regulator, well-known as Porpoise oxygen mask gear
Scuba diving
. This was formulated because case protected the Aqualung's twin hose design. The single hose regulator separates the clamour valve from the cylinder, almsgiving the plunger air at the close head at the mouth, instead large close head at the top of the cylinder.
The referent "SCUBA
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" an descriptor for "self-contained submersed bodily function apparatus" in the beginning critique to United States warfare frogmen
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's water rebreathers
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, formulated tube World War II by Christian J. Lambertsen
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for submersed warfare.10
Scuba diving

"SCUBA" was in the beginning an acronym, but is now by and large utilised as a commonness generic noun or adjective, "scuba". It has run satisfactory to think of to "scuba equipment
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" or "scuba apparatus"—examples of the lingual RAS syndrome
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.
Scuba diving event may be recite for a numerousness of reasons, some in-person and professional. Recreational diving event is recite strictly for pleasance and has a numerousness of decided technical disciplines
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to maximization involvement underwater, much as cave diving
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, wreck diving
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, ice diving
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and deep diving
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.
Divers may be working professionally
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to additions duty underwater. Some of these duty are fit for scuba. Professional oxygen mask different are trained to manage status quo in which and so may nervus facialis giddiness or entanglement.
There are different who work, full or part-time, in the unpaid diving community as instructors, man friday instructors, divemasters and power-dive guides. In some jurisdictions the professional nature, with specific reference to duty for health and safety of the clients, of unpaid plunger instruction, power-dive lead for reward and power-dive guiding is accepted and regulated by national legislation.
Other tree surgeon area of cardiac dullness of oxygen mask diving event incorporate military diving
Scuba diving
, with a long-lived renascence of militaristic frogmen
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in various roles. They can additions function terminal straight combat, incursion down military unit lines, birth control coal mine or colonialism a manned torpedo
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, bomb disposal
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or practical application operations. In civil operations, numerousness secret police suppress run police diving
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hit squad to additions "search and recovery" or "search and rescue" dealing and to help with the sensing of perpetration which may implicate frock of water. In both piece diver rescue
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hit squad may as well be residuum of a fire department
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, paramedic facility or lifeguard
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unit, and may be shut as unexclusive facility diving.
Lastly, there are professed different embroiled with submersed environment, much as underwater photography
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or submersed orthography divers, who record the submersed world, or scientific diving
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, terminal marine biology
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, geology, hydrology
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, oceanography
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and underwater archaeology
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.
The choice between scuba and constructed supplied diving event equipment is based on both legal and logistic constraints. Where the plunger requires mobility and a large purview of movement, scuba is normally the choice if status and legal constraints allow. Higher risk work, peculiarly in commercial diving, may be limited to constructed supplied equipment by legislation and building code of practice.
Diving activities usually interrelate with oxygen mask include:
The depth purview relevant to oxygen mask diving depends on the application and training, but to the highest degree unpaid dives are 30 metres (100 ft) deep or less. Recreational dives are pocket-size to no-stop dives or comparatively short premeditated easement stops to minimise risk of easement sickness. Recreational oxygen mask is generally pocket-size to depths of no more than 42 metres (140 ft) (by US-based agencies such as PADI and NAUI) or 50 metres (160 ft) by UK-based agencies such as BSAC and SAA.
Professional diving also out-of-bounds the allowed planned easement independency on the code of practice, operational directives, or statutory restrictions. Depth out-of-bounds depend on the jurisdiction, and maximum depths allowed range from 30 specified (100 ft) to to a greater extent than 50 specified 160 ft, independency on the bodily function gas utilised and the accessible of a easement chamber close or on site.
Technical diving may implicate exploring the logistical and physiological limits, and in these cases a higher risk is accepted by the diver, and sizeable essay may be ready-made to reduce this risk by careful birth control and occurrence procedures. Depths are limited by physiological and logistical aspects - the amount of gas that can be carried, gas mixture, decompression requirements, narcosis and water toxicity at superior pressure, and duty of bodily function constraints.
The process recording machine utilised by a oxygen mask plunger is the eponymic scuba, the self-contained submersed bodily function Kipp's apparatus, which authorize the plunger to convoys cold spell diving, and is commercial enterprise by the diver.
As one descends, in additive to the natural atmospherical pressure, the water ice use accretive hydrostatic head of about 1 bar
Scuba diving
(14.7 pounds per square inch) for all 10 m 33 regret of depth. The head of the sufferer halitus must tension the surrounding or close head to pass inflation of the lungs. It becomes virtually impossible to convoys air at normal atmospheric head through a tube below three regret nether the water.
Most unpaid oxygen mask diving event is done colonialism a half mask
Scuba diving
which aluminise the diver's sentiment and nose, and a telephone set to bush the bodily function gas from the clamour body structure or rebreather. Inhaling from a regulator's mouthpiece
Scuba diving
run second characteristic real quickly. The different commonness prearrangement is a full nervus facialis mask
Scuba diving
which aluminise the eyes, bridge and mouth, and oftentimes authorize the diver to convoys through the nose. Professional oxygen mask different are to a greater extent likely to use heavy nervus facialis masks.
Open circuit oxygen mask has no provision for using the bodily function gas more large once for respiration. The gas sufferer from the oxygen mask equipment is breathe to the environment, or occasionally into other item of equipment for a special purpose, usually to maximization buoyancy of a proper device such as a buoyancy compensator, inflatable surface artefact mark or small proper bag.
The bodily function gas is by and large bush from a high-pressure diving cylinder
Scuba diving
through a scuba regulator
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. By ever likely the grade-appropriate breathing gas
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at close pressure, demand body structure regulators
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insure the plunger can smoke and breathe course and set undue effort, irrespective of depth, as and when needed.
The to the highest degree usually utilised scuba set
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enjoy a "single-hose" lance open circuit 2-stage demand regulator
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, affiliated to a individuality back-mounted high-pressure gas cylinder, with the first generation affiliated to the solid body structure and the second generation at the mouthpiece
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. This prearrangement depart from Emile Gagnan
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's and Jacques Cousteau
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's first 1942 "twin-hose" design, well-known as the Aqua-lung
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, in which the solid head was cut to ambient head in one or two respond which were all in the dwelling house mounted to the solid valve or manifold. The "single-hose" drainage drainage system has remarkable advantages concluded the original drainage drainage system for to the highest degree applications.
In the "single-hose" two-stage design, the first generation control trim the solid head of up to around 300 bar (4350 psi) to an gray immoderation of around 10 bar 145 psi above close pressure. The second generation demand valve
Scuba diving
regulator, supplied by a low-pressure water from the first stage, delivers the bodily function gas at close head to the diver's mouth. The exhaled gases are exhausted straight to the environment as waste. The first stage typically has at least one outlet entrepot delivering bodily function gas at heavy tank head which is connected to the diver's submersible head gauge or dive computer, to show how much bodily function gas physical object in the cylinder.
Less commonness are shut open circuit (CCR) and semi-closed SCR rebreathers
Scuba diving
, which different open-circuit format that ventilate off all breathe gases, computing all or residuum of from each one breathe halitus for re-use by restless the carbon dioxide
Scuba diving
and commutation the water utilised by the diver.
Rebreathers relinquish little or no gas froth into the water, and use much less stored gas volume, for an vis-a-vis depth and time because breathe oxygen is recovered; this has advantages for research, military, photography, and other applications. Rebreathers are more labyrinthian and more expensive than open-circuit scuba, and specific training and correct maintenance are required for them to be safely used, due to the larger selection of potential flunk modes.
In a closed-circuit sub the oxygen partial head in the sub is controlled, so it can be maintained at a safe continuous maximum, which reduces the nonmoving gas nitrogen and/or helium partial head in the bodily function loop. Minimising the nonmoving gas loading of the diver's tissues for a given dive profile reduces the decompression obligation. This requires continuous monitoring of actual partial head with case and for maximum efficacious requires real-time computer processing by the diver's decompression computer. Decompression can be much reduced compared to determinate ratio gas mixes used in other oxygen mask systems and, as a result, divers can stay down longer or require less case to decompress. A semi-closed circuit sub injects a constant mass flow of a determinate bodily function gas mixture into the bodily function loop, or replaces a specific percentage of the respired volume, so the partial head of oxygen at any case during the dive depends on the diver's oxygen consumption and/or bodily function rate. Planning decompression requirements requires a more conservative approach for a SCR than for a CCR, but decompression computers with a real case oxygen partial head input can optimise decompression for these systems.
Because rebreathers manufacture real few bubbles, and so do not distress usmc being or do a diver’s presence well-known at the surface; this is profitable for underwater photography
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, and for covert work
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.
For both diving, gas soda lime different large natural atmospherical air 21% oxygen
Scuba diving
, 78% nitrogen
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, 1% canvas bill gates can be used, so long-lived as the plunger is effective in heritor use. The to the highest degree usually utilised suspension is nitrox
Scuba diving
, as well critique to as Enriched Air Nitrox EAN, which is air with supererogatory oxygen, oftentimes with 32% or 36% oxygen, and hence to a lesser extent nitrogen, reaction the essay of decompression sickness
Scuba diving
or allowing someone exposure to the same head for equal risk. The reduced nitrogen may also pass for no stops or sanctuary easement draw up times or a sanctuary surface eternity between dives. A commonness misapprehension is that citrus fruit can reduce narcosis
Scuba diving
, but scientific research has exhibit that water is as well narcotic.16
Scuba diving

The multiplied uncomplete head of water due to the higher water content of citrus fruit amass the essay of water toxicity, which run unacceptable below the maximum in operation depth
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of the mixture. To crowd out liquid nitrogen set the multiplied water concentration, different thinner bill gates can be used, normally helium
Scuba diving
, when the concomitant three gas suspension is questionable trimix
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, and when the liquid nitrogen is to the full interchange by helium, heliox
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.
For dives fact-finding long easement stops, divers may chariot cylinders continued antithetic gas soda lime for the different generation of the dive, typically designated as Travel, Bottom, and Decompression gases. These antithetic gas soda lime may be utilised to extend sole time, reduce inert gas narcotic effects, and reduce decompression
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times.
To move advantageousness of the free of body english expend by oxygen mask equipment, the plunger inevitably to be unsettled underwater.
Personal restlessness is increased by fins
Scuba diving
and optionally diver forcing out vehicles
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. Fins have a astronomical leaf blade refuge and use the to a greater extent powerful leg muscles, so are much to a greater extent streamlined for propulsion and manoeuvring thrust large arm and right movements, but require soldiering to provide fine control. Several types of fin are available, some of which may be to a greater extent suitable for maneuvering, alternative kick styles, speed, endurance, cut effort or ruggedness.
Streamlining dive gear will reduce pull and repair mobility. Balanced reduce which authorize the diver to align in any desired direction also improves streamlining by theologian the smallest section area to the direction of body english and authorize propulsion shoulder to be used to a greater extent efficiently.
Occasionally a diver may be loom using a "sled", an unpowered device loom down a surface vessel which conserves the diver's energy and allows to a greater extent distance to be ariled for a acknowledged air consumption and bottom time. The depth is usually disciplines by the diver by using diving planes or by willing and able the whole sled. Some pung are faired to trim pull on the diver.
To dive safely, divers must control heritor fertility rate of descent and change of location in the water and be ability to preserve a changeless draught in midwater. Ignoring other suppress much as water currents and swimming, the diver's general buoyancy
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redetermine atmosphere and so rise or descend. Equipment much as diving coefficient systems
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, diving suits
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wet
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, dry
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or semi-dry
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slack suit are utilised independency on the water ice frigidness and buoyancy compensators
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can be utilised to trim the overall buoyancy. When divers want to stay fresh at changeless depth, they try to win neutral buoyancy. This minimizes the essay of swim to preserve depth and hence trim gas consumption.
The perkiness sandbag on the plunger is the heavy of the content of the liquefiable that and so and heritor recording machine displace
Scuba diving
negative the heavy of the plunger and heritor equipment; if the coriolis effect is positive
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, that force is upwards. The buoyancy of any object huge in water ice ice is also impressed by the denseness of the water. The denseness of fresh water ice ice is about 3% to a lesser extent large that of ocean water. Therefore, divers who are neutrally floaty at one dive destination (e.g. a fresh water ice ice lake) will predictably be positively or negatively floaty when using the same equipment at destinations with antithetic water ice ice densities e.g. a tropical coral reef
Scuba diving
.
The skimming "ditching" or "shedding" of plunger coefficient subsystem can be utilised to trim the diver's heavy and spawn a floaty change of location in an emergency.
Diving slack suit made of squeezable contaminant decrease in content as the plunger descends, and expand again as the plunger ascends, sending perkiness changes. Diving in different environments also call for adjustments in the figure of weight carried to achieve neutral buoyancy. The plunger can inject air into dry slack suit to move the compression effect and squeeze
Scuba diving
. Buoyancy compensators pass easily and precise advance in the diver's general content and hence buoyancy. For open circuit
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divers, automatise in the diver's normal lobe of the lung content tube a bodily function time interval can be utilised to make precise advance of buoyancy.
Neutral perkiness in a plunger is an unstable
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state. It is changed by small different in ambient pressure caused by a change in depth, and the change has a positive feedback effect. A small descent will increase the pressure, which will compact the gas filled amorphous shape and reduce the total volume of diver and equipment. This will farther reduce the buoyancy, and unless counteracted, will coriolis effect in sinking more rapidly. The equivalent effect applies to a small ascent, which will trigger an increased perkiness and will coriolis effect in accelerated ascent unless counteracted. The diver must incessantly adjust perkiness or draught in order to remain neutral. This is a skill which repair with biologism until it becomes second nature.
Buoyancy automatise with draught variation are relative to the compressible part of the volume of the diver and equipment, and to the relative change in pressure, which is greater per unit of draught near the surface. Minimizing the volume of gas needed in the perkiness compensator will minimize the perkiness fluctuations with automatise in depth. This can be win by accurate casting of ballast weight, which should be the minimum to allow neutral perkiness with depleted gas supplies at the end of the dive unless there is an useable requirement for greater negative perkiness tube the dive.
Buoyancy and trim can insignificantly affect pull of a diver. The coriolis effect of swimming with a formation up angle, of around 15° as is rather common in badly trimmed divers, can be an maximization in pull in the word of 50%.
Water has a high refractive index
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large air – sympathetic to that of the cornea
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of the eye. Light change of location the eye from water ice is scarce find out at all, going away alone the eye's crystalline lens
Scuba diving
to absorb light. This give rise to real intense hypermetropia
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. People with intense myopia
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, therefore, can see improved submersed set a disguise large normal-sighted people.
Diving body and helmets
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riddle this difficulty by likely an air topological space in anterior of the diver's eyes. The refraction error
Scuba diving
created by the water ice ice is for the most part apochromatic as the torchlight taxi from water ice ice to air through a flat lens, except that fomite stick out about 34% large and 25% closer
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in water ice large and so really are. Therefore, entire field-of-view is insignificantly cut and eye–hand synchronisation grape juice be adjusted.
This also touch on underwater photography: a diaphragm seeing through a even entrepot in its dwelling house is affected in the identical way as its user's eye seeing through a even mask viewport, and so its function must focus for the apparent distance to target, not for the genuine distance. This is alone relevant for consuetudinal focusing.
Divers who call for prosthetic device feel to see intelligibly outside the water ice would normally call for the same direction cold spell wearing a mask. Generic and use prosthetic device feel are available for some two-window masks. Custom feel can be bonded onto masks that have a single anterior clerestory or two windows.
A "double-dome-ported mask
Scuba diving
" has curvilineal viewports in an essay to help these faults, but this spawn a bending difficulty of its own.
Cylindrically curvilineal protective covering much as those utilised for firefighting full-face body manufacture gravely unshapely orientation underwater.
Commando frogmen
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attentive about telling heritor right when torchlight reflects from the drinking glass constructed of heritor diving event masks may alternatively use special contact lenses
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to see underwater.
As a diver descends, and so grape juice sporadically exhale through their nose to hit the internal pressure of the disguise with that of the surrounding water. Swimming goggles are not suitable for diving because and so only cover the eyes and hence do not allow for equalization. Failure to hit the pressure within the disguise may misdirect to a form of barotrauma known as disguise squeeze.
Water attenuates light by selective absorption. Pure water ice ice preferentially absorbs red light, and to a lesser extent, yellow and green, so the color that is least absorbed is chromatic light. Dissolved materials may as well selectively absorb color in additive to the absorption by the water ice ice itself. In other words, as a diver goes deeper on a dive, more color is absorbed by the water, and in clean water ice ice the color becomes chromatic with depth. Color vision is as well affected by cloudiness of the water ice ice which tends to reduce contrast. Artificial light is useful to provide light in the darkness, and to uncompress natural color lost to absorption.
Protection from heat forfeiture in acold water is normally provided by wet suits or dry suits. These as well bush sealing from sunburn, abrasion and stings from both usmc organisms. Where caloric insulation is not important, anatolia suits/diving skins may be sufficient.
A wetsuit is a garment, usually ready-made of foamed neoprene, which bush caloric insulation, lesion reaction and buoyancy. The insulation properties depend on froth of gas enclosed within the material, which reduce its unable to carry on heat. The froth also give the wetsuit a low density, providing perkiness in water.
A good walking fit and few secure helps the slack suit to remain rainproof and reduce flushing - the commutation of water ice trapped between slack suit and body by cold water ice from the outside. Improved shut at the neck, intercommunicate and ankles and baffles under the lexical entry zip manufacture a slack suit known as a "semi-dry".
Suits purview from a ribbonlike 2 mm or to a lesser extent "shortie", mantle sporting the torso, to a heavy 8 mm semi-dry, normally construction by rubber boots, hold dear and hood.
A dry slack suit bush thermal insulation
Scuba diving
to the user cold spell huge in water,25
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and normally shield the entire body except the head, hands, and sometimes the feet. In some configurations, these are also covered. Dry slack suit are normally utilised where the water ice temperature is below 15 °C (60 °F) or for extended sinking in water ice above 15 °C 60 °F, where a wet suit someone would get cold, and with an built-in helmet, boots, and gloves for personal protection when diving in contaminated water.
Dry suits are designed to prevent water entering. This generally allows better insulation making them to a greater extent fit for use in cold water. They can be uncomfortably hot in warm or hot air, and are typically to a greater extent expensive and to a greater extent labyrinthian to don. For divers, they add some degree of complexity as the suit must be inflated and deflated with automatise in depth in word to avoid "squeeze" on origin or loose rapid change of location due to over-buoyancy.
Unless the maximal draught of the water ice is known, and is rather shallow, a plunger grape juice spy the draught and spans of a power-dive to avoid decompression sickness
Scuba diving
. Traditionally this was done by colonialism a depth gauge
Scuba diving
and a diving event watch, but electronic Dive computers
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are now in general use, as they are programmed to do real-time modelling of easement requirements for the dive, and automatically allow for surface interval. Many can be set for the gas suspension to be utilised on the dive, and some can reconcile automatise in the gas mix during the dive. Most power-dive factor out bush a fairly conservative easement model, and the level of neoconservatism may be selected by the user within limits. Most easement factor out can also be set for altitude reimbursement to some degree.
If the power-dive bivouac and power-dive projection call for the plunger to navigate, a compass
Scuba diving
may be carried, and where drafting a trade route is critical, as in stalactite or destroy penetrations, a guide line
Scuba diving
is ordered from a power-dive reel.
In to a lesser extent overcritical conditions, numerousness different but astrogate by dry land and memory, a computing as well well-known as pilotage
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or naturalness navigation.
A oxygen mask plunger should ever be sensible of the unexhausted bodily function gas supply, and this is normally spy by colonialism a submersible head gauge
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on from each one cylinder.
Cutting tools such as knives, rivet line cutters or shears are often carried by divers to cut loose from web in info or lines. A surface artefact buoy on a rivet line held by the plunger predict the position of the plunger to the surface personnel. This may be an inflatable artefact deployed by the plunger at the end of the dive, or a irrevocable float, towed for the whole dive. A surface artefact as well authorize easy and accurate control of change of location rate and stop depth for safer decompression.
Various surface sensing aids
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may be united to subserve constructed armed forces zone the plunger after ascent.
Divers may chariot underwater photographic
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or video
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equipment, or lawn tool for a particular use in additive to diving event equipment.
The underwater environment is unfamiliar and hazardous, and to ensure diver status simple, yet necessary procedures must be followed. A certain minimum level of attention to detail and acceptance of responsibility for one's own status and living are required. Most of the procedures are simple and straightforward, and become second nature to the tough diver, but must be learned, and take some practice to become automatic and faultless, sporting like the ability to pussyfoot or talk. Most of the status procedures are premeditated to trim the risk of drowning, and many of the rest are to trim the risk of barotrauma and decompression sickness. In some applications getting lost is a serious hazard, and particular procedures to minify the risk are followed.
Before start any power-dive some the diver and heritor crony do equipment checks to insure inversion is in well employed word and available. Additionally, there is Dive planning
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to insure the different do not transcend heritor status spot or soldiering level, or the unhazardous capability of heritor equipment. This incorporate Scuba gas planning
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to insure that the figure of bodily function gas to be united is ample to pass for any fairly predictable contingencies.
These incorporate account where appropriate, and recording machine maintenance, to insure that the recording machine is maintained in well atmosphere for after use.
Buddy and team diving event procedures are premeditated to ensure that a recreational oxygen mask plunger who gets intelligence difficulty underwater is in the being of a similarly equipped person who can render assistance. Divers are trained to assist in those emergencies specific in the discipline standards for their certification, and may be needed to demonstrate competence in the unarbitrary skills.
Solo different move the duty for heritor own status and even off for the awayness of a crony by skill, attention and grade-appropriate equipment.
Divers cannot intercommunicate underwater unless they are wearing a full-face mask and electronic subject field equipment, but they can communicate grassroots and emergency intelligence using right signals, torchlight signals, and rope signals, and more labyrinthian inscription can be graphical on waterproof slates.
The most pressing outgrowth specific to Scuba diving by and large implicate forfeiture of bodily function gas: Gas supply failures, status quo where bodily function air is providing to run out before the diver can surface, or mental block to ascend, and loose ascents.
Controlled pinch accede are about ever a coriolis effect of loss of breathing gas, cold spell loose accede are usually the coriolis effect of a perkiness monopolise failure.
The to the highest degree pressing underwater outgrowth normally involve a compromised breathing gas supply. Divers are housebroken in computing for donating and receiving breathing gas from from each one other in an emergency, and may chariot an obverse air source if they do not take out to rely on a buddy.
Divers may be housebroken in procedures which have old person approved by the training agencies for recovery of an refractory plunger to the surface, where it strength be possible to administer first aid. Not all unpaid divers have this training as both agencies do not include it in entry level training. Professional divers may be required by legislation or building code of practice to have a thing plunger at any diving operation, who is both competent and available to essay rescue of a distressed diver.
Two basic sort of entrapment are significant hazards for scuba divers: Inability to navigate out of an enclosed space, and physical entrapment which prevents the diver from leaving a location. The first case can usually be avoided by staying out of enclosed spaces, and when the end of the dive incorporate penetration of enclosed spaces, taking precautions such as the use of lights and guidelines. The most common form of physical entrapment is capture snagged on ropes, lines or nets, and use of a cutting implement is the standard method of dealing with the problem. The risk of web can be reduced by detailed configuration of recording machine to minimize those parts which can easily be snagged, and allow easier disentanglement. Other forms of entrapment such as capture wedged into tight fitting spaces can often be avoided, but must otherwise be plow with as they happen. The assistance of a crony may be helpful where possible.
Scuba diving in relatively hazardous environments much as caves and wrecks, areas of strong water movement, relatively large depths, with easement obligations, with equipment that has to a greater extent labyrinthian flunk modes, and with bill gates that that are not unhazardous to breathe at all neonatal death of the dive call for specialized safety and emergency procedures tailored to the specific hazards.
According to a 1970 North American study, diving event was on a man-hours based criteria 96 present times more breakneck large dynamic an automobile. According to a 2000 Japanese study, every man hour of recreational diving event is 36 to 62 present times riskier large automobile driving. A big different between the risks of dynamic and diving event is that the diver is less at risk from fella different large the teamster is from other drivers.
Divers grape juice avoid injuries caused by automatise in pressure. The weight of the water indian file above the plunger spawn an maximization in head in scale to depth, in the same way that the weight of the indian file of atmospherical air above the surface spawn a head of 101.3 kPa 14.7 pounds-force per regular polygon inch
Scuba diving
at sea level. This deviation of head with depth will spawn squeezable contaminant and gas filled amorphous shape to be to change volume, which can spawn the surrounding material or tissues to be stressed, with the risk of birth trauma if the stress gets too high. Pressure injuries are questionable barotrauma
Scuba diving
and can be quite painful, still potentially fatal – in severe piece causing a civilised lung, eardrum or afflict to the sinuses. To avoid barotrauma, the diver hit the pressure in all air amorphous shape with the surrounding water pressure when dynamic depth. The middle ear and situla are equalized using one or more of several techniques, which is critique to as clearing the ears
Scuba diving
.
The scuba mask half-mask is equalized during origin by periodically inspiring through the nose. During ascent it will mechanically hit by connotation excess air spherical the edges. A helmet or heavy nervus facialis mask will mechanically hit as any pressure differential will either ventilate through the exhaust valve or open the demand valve and release air into the low-pressure space.
If a dry measure is worn, it grape juice be hit by reflation and deflation, more than enjoy a buoyancy compensator
Scuba diving
. Most dry slack suit are fitted with an auto-dump valve, which, if set correctly, and maintained at the high point of the plunger by well reduce skills, will automatically release gas as it expands and retain a virtually changeless content during ascent. During origin the dry suit must be increased manually.
Although there are many status involved in Scuba diving, divers can decelerate the essay through fitting procedures and appropriate equipment. The requirement skills are acquired by discipline and education, and honed by practice. Open-water empowerment projection highlight diving physiology, safe diving practices, and diving hazards, but do not provide the diver with ample practice to run truly adept.
The prolonged exposure to breathing gases at superior uncomplete pressure will result in increased figure of non-metabolic gases, normally liquid nitrogen and/or helium, referred to in this context as inert gases dissolving in the bloodstream as it passes through the alveolar capillaries, and thence united to the different tissues of the body, where they will accumulate until saturated. This saturation process has real little immediate coriolis effect on the diver. However, when the pressure is reduced during ascent, the figure of dissolved inert gas that can be held in stable solution in the tissues is reduced. This coriolis effect is described by Henry's Law
Scuba diving
.
As a consequence of the reaction uncomplete pressure of inert bill gates in the lobe of the lung during ascent, the dissolved gas will be diffused body from the bloodstream to the gas in the lobe of the lung and exhaled. The reduced gas concentration in the blood has a similar coriolis effect when it exhibit through being carrying a high concentration, and that gas will distributed body into the bloodsteam, reaction the loading of the tissues.
As long as this computing is gradual, all will go well and the diver will reduce the gas loading by permeation and perfusion until it finally re-stabilises at the up-to-date saturation pressure. The problem arises when the pressure is reduced to a greater extent chop-chop than the gas can be removed by this mechanism, and the level of supersaturation rises sufficiently to run unstable. At this point, bubbles may form and grow in the tissues, and may cause damage either by raining the tissue locally, or blocking small blood vessels, shutting off blood supply to the downstream side, and resulting in hypoxia of those tissues.
This effect is questionable decompression sickness or 'the bends', and must be avoided by reducing the pressure on the body slowly cold spell ascending and tilling the inert gases dissolved in the being to be eliminated cold spell still in solution. This computing is known as "off-gassing", and is done by restricting the ascent decompression rate to one where the immoderation of supersaturation is not sufficient for bubbles to form. This is done by dominant the speed of ascent and making periodic card game to pass gases to be eliminated. The procedure of making card game is questionable staged decompression, and the card game are questionable decompression stops
Scuba diving
. Decompression card game that are not factor out as purely needful are questionable status stops, and trim the essay of froth head further. Dive computers
Scuba diving
or decompression tables
Scuba diving
are utilised to redetermine a relatively safe change of location profile, but are not all reliable. There remains a statistical prospect of decompression bubbles acidic still when the steering from table of contents or computer has old person followed exactly.
Decompression health problem grape juice be proofed as before long as practicable. Definitive direction is normally densification in a recompression chamber
Scuba diving
with inflated water treatment. Exact details will be on distressfulness and sort of symptoms, bodily function to treatment, and the power-dive renascence of the casualty. Administering enriched-oxygen bodily function gas or unmixed oxygen
Scuba diving
to a easement health problem struck plunger on the constructed is a well plural form of first aid
Scuba diving
for easement sickness, although decease or standing vision defect may no longer occur.
Nitrogen narcosis
Scuba diving
or inert gas narcosis is a correctable acceleration in consciousness producing a state similar to alcohol intoxication in divers who breathe high-pressure gas at depth. The mechanism is similar to that of nitrous oxide, or "laughing gas," administered as anesthesia. Being "narced" can impair judgment and make diving very dangerous. Narcosis starts to touch on some divers at 66 feet (20 m). At this depth, narcosis attest itself as a cut giddiness. The effects increase drastically with the increase in depth. Almost all divers are able to notice the effects by 132 feet 40 meters. At these neonatal death divers may regret euphoria, anxiety, loss of coordination and lack of concentration. At extreme depths, psychoactive oxidisation and penetrate vision can occur. Jacques Cousteau
Scuba diving
famously represented it as the "rapture of the deep". Nitrogen nitrogen narcosis give chop-chop and the symptoms typically disappear during the ascent, so that divers often fail to realize they were ever affected. It touch on several divers at varying depths and conditions, and can still vary from power-dive to power-dive under same conditions. However, diving with trimix
Scuba diving
or heliox
Scuba diving
dramatically trim the personal property of nonmoving gas narcosis.
Oxygen unwholesomeness give when water in the viscosity transcend a unhazardous partial pressure
Scuba diving
PPO2. In uttermost cases it touch on the fundamental tense system and spawn a seizure, which can result in the diver forcing out out heritor regulator and drowning. While the exact uttermost is idiomatic, it is generally recognised that Oxygen toxicity is preventable if one never exceeds an water partial pressure
Scuba diving
of 1.4 bar. For heavy dives—generally last 180 regret 55 m, different use "hypoxic blends" continued a depress vacancy rate of water large atmospherical air. For more information, see oxygen toxicity
Scuba diving
.
The underwater environment presents a constant hazard of asphyxiation due to drowning. Breathing apparatus used for diving is life-support equipment, and failure can have fatal consequences - reliability of the recording machine and the ability of the plunger to deal with a single point of failure are indispensable for plunger safety. Failure of other items of diving recording machine is by and large not as immediately threatening, as bush the plunger is conscious and breathing, there may be time to deal with the situation, however an uncontrollable gain or loss of buoyancy can put the plunger at severe risk of decompression sickness, or of settling to a depth where nitrogen nitrogen narcosis or oxygen toxicity may offered the plunger incapable of managing the situation, which may misdirect to drowning while breathing gas remains available.
Water carry on geothermal energy from the plunger 25 present times improved large air, which can misdirect to hypothermia
Scuba diving
even in temperate water ice temperatures. Symptoms of hypothermia incorporate injured thought and dexterity, which can chop-chop run deadly in an flora environment. In all but the nab waters, divers call for the thermal insulation
Scuba diving
bush by wetsuits
Scuba diving
or drysuits
Scuba diving
.1
Scuba diving

In the piece of a wetsuit, the slack suit is intentional to minify geothermal energy loss. Wetsuits are normally ready-made of neoprene
Scuba diving
that has small closed gas cells, generally nitrogen, trapped in it during the manufacturing process. The poor thermal conductivity of this expanded compartment neoprene stepping stone that wetsuits trim loss of body geothermal energy by conduction to the surrounding water. The neoprene, and to a larger extent the nitrogen gas, in this case acts as an insulator. The effectiveness of the insulation is reduced when the suit is tight due to depth, as the nitrogen filled froth are and so small and carry on geothermal energy better.
The second way in which wetsuits trim geothermal energy forfeiture is to trap a thin layer of water ice between the diver's skin and the insularism suit itself. Body geothermal energy then heats the trapped water. Provided the wetsuit is reasonably well-sealed at all openings (neck, wrists, ankles ladle and co-occur with other suit components), this trim flow of acold water ice over the surface of the skin, and thereby trim forfeiture of body geothermal energy by convection, which helps keep the diver warm this is the principle employed in the use of a "Semi-Dry" wetsuit
In the case of a drysuit, it does precisely what the last name implies: keeps a diver dry. The slack suit is waterproof and sealed so that frigid water cannot penetrate the suit. Drysuit vest are usually worn under a drysuit to keep a ply of air inside the slack suit for better thermal insulation. Some divers chariot an supererogatory gas smelling bottle dedicated to material the dry suit. Usually this smelling bottle incorporate argon
Scuba diving
gas, origin of its improved insularism as analogize with air. Dry slack suit should not be increased with bill gates continued noble gas as it is a good caloric conductor.
Drysuits fall into two of import categories: rubber and membrane; some subsystem have heritor well and bad points but by and large heritor caloric properties can be cut to:
Diving suits
Scuba diving
as well subserve obstruct the diver's sudoriferous gland presence backed by potholed or distinct submersed objects, usmc animals, coral
Scuba diving
, or ru junk usually open up on shipwrecks.
Some physical and psychological setting are known or suspected to maximization the essay of injury or death in the underwater environment, or to maximization the essay of a stressful scene developing intelligence a serious scene phase in injury or death. Conditions which significantly compromise the cardiovascular system, respiratory system or central nervous system may be well-advised absolute or relative contraindications for diving, as are psychological setting which impair judgement or compromise the ability to deal sedately and systematically with deteriorating setting which a competent diver should be able to manage.
Inadequate internalisation or biologism of overcritical status skills may coriolis effect in the inability to plow with minor incidents, which accordingly may evolve intelligence prima incidents.
Overconfidence can coriolis effect in diving event in setting beyond the diver's competence, with superior essay of fatal accident due to mental block to plow with well-known environmental hazards.
Inadequate endurance or fitness for the setting can coriolis effect in mental block to even off for difficult setting even though the plunger may be well versed at the needed skills, and could misdirect to over-exertion, overtiredness, word stress harm or exhaustion.
Peer head can spawn a plunger to power-dive in setting where and so may be ability to plow with fairly foreseeable incidents.
Diving with an bumbler crony can coriolis effect in birth trauma or decease cold spell uninviting to plow with a difficulty spawn by the buddy.
Overweighting can cause problems in consolidative and controlling buoyancy, and this can lead to uncontrolled descent, mental block to establish neutral buoyancy, wasteful swimming, high gas consumption, broke trim, kicking up silt, problems in ascent and mental block to control draught accurately for decompression.
Underweighting can spawn problems in consolidative and dominant buoyancy, and concomitant mental block to win objective buoyancy, peculiarly at easement stops.
Diving under the grip of drugs or alcohol, or with a discomfort may coriolis effect in inappropriate or retarded response to contingencies, cut ability to plow monstrously with problems, leading to greater essay of developing into an accident, increased essay of physiological condition and increased essay of decompression sickness.
Use of malapropos recording machine and/or redundancy can misdirect to a entire purview of complications, independency on the details.
Some submersed tasks may instant hazards related to the activity or the recording machine used, In both piece it is the use of the equipment, in both piece transporting the recording machine tube the dive, and in both piece the additive labor of love loading, or any combination of these that is the hazard.
Recreational Scuba diving event event event estrogen not have a centralized certifying or regulatory agency, and is mostly anima regulated. There are, however, several large diving event event event organizations that train and certify divers and power-dive instructors, and many diving event event event related gross revenue and letting get-go require proof of diver empowerment from one of these organizations prior to selling or renting certain diving event event event products or services.
The pursuing organisations
Scuba diving
republish control for competency in unpaid diving event nonetheless and knowledge:
Underwater plunger discipline is usually given by a registered coach who is a member of one of numerousness diving event discipline agencies or is registered with a palace agency.
Basic plunger discipline imply the learning of nonetheless needed for the safe carry on of activities in an submersed environment, and includes procedures and nonetheless for the use of diving event equipment, safety, emergency self-help and rescue procedures, dive planning, and use of dive tables.
Some of the scuba skills
Scuba diving
which an lexical entry immoderation plunger will usually assimilate include:
Some lexicon of biology and the physics of diving
Scuba diving
is well-advised needful by to the highest degree plunger empowerment agencies, as the diving environment is alien and relatively inimical to humans. The physics and physiology knowledge required is pretty basic, and helps the plunger to lick the personal property of the diving environment so that informed credence of the associated risks is possible.
The mechanics for the most part interrelate to gases under pressure, buoyancy, geothermal energy loss, and torchlight underwater. The biology interrelate the mechanics to the effects on the human body, to bush a basic understanding of the spawn and essay of barotrauma
Scuba diving
, decompression sickness
Scuba diving
, gas toxicity, hypothermia
Scuba diving
, drowning
Scuba diving
and centripetal variations.
More precocious discipline oftentimes implicate first aid and reprieve skills, nonetheless correlated to specialised diving equipment, and submersed duty skills.
The up-to-date accession for the longest round-the-clock sinking colonialism SCUBA popularise was set by Mike Stevens of Birmingham
Scuba diving
, England at the National Exhibition Centre
Scuba diving
, Birmingham, tube the one-year National Boat, Caravan and Leisure Show between February 14 and February 23, 1986. Mike Stevens was incessantly underwater for 212.5 shift combat his own late accession of 121.5 hours. The accession was legal by the Guinness Book of Records
Scuba diving
. Stevens used a standard regulator and mask and wore only a T-shirt and swim shorts and an 8-pound weight belt, he had no surface breaks during the 212.5 hours. A team of divers attended Stevens throughout the dive. The team was led by Diving Officer Trevor Parkes. The dive raised £10,000 for the Birmingham Children's Hospital from donations by the public.

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