Scuba (originally an acronym for Self Contained Underwater Breathing Apparatus) diving is swimming underwater, or taking part in another activity, while using a scuba set.[1] By carrying a source of breathing gas (usually compressed air),[2] the scuba diver is able to stay underwater longer than with the simple breath-holding techniques used in snorkeling and free-diving, and is not hindered by air lines to a remote air source. The scuba diver typically swims underwater by using fins attached to the feet. However, some divers also move around with the assistance of a DPV (diver propulsion vehicle), commonly called a "scooter", or by using surface-tethered devices called sleds pulled by a boat.
For the history of diving, see timeline of underwater technology.
Contents [hide]
1 History
2 Etymology
3 Types of diving
4 Physiological issues
4.1 Breathing underwater
4.2 Open-circuit
4.3 Rebreather
4.4 Gas mixtures
4.5 Injuries due to changes in air pressure
4.6 Effects of breathing high pressure gas
4.6.1 Decompression sickness
4.6.2 Nitrogen narcosis
4.6.3 Oxygen toxicity
4.7 Refraction and underwater vision
4.8 Controlling buoyancy underwater
4.9 Avoiding losing body heat
4.10 Avoiding skin cuts and grazes
4.11 Diving longer and deeper safely
4.12 Being mobile underwater
5 Scuba dive training and certification agencies
6 See also
7 Reference list
8 Further reading
9 External links
History
Scuba today typically refers to the in-line open-circuit equipment, developed by Emile Gagnan and Jacques-Yves Cousteau, in which compressed gas (usually air) is inhaled from a tank and then exhaled into the water. However, rebreathers (both semi-closed circuit and closed circuit) are also self-contained systems (as opposed to surface-supplied systems) and are therefore classified as scuba.
[edit]Etymology
The term SCUBA (an acronym for Self-Contained Underwater Breathing Apparatus) arose during World War II, and originally referred to United States combat frogmen's oxygen rebreathers, developed by Dr. Christian Lambertsen for underwater warfare.[2][3][4].
The word SCUBA began as an acronym, but it is now usually thought of as a regular word—scuba. It has become acceptable to refer to "scuba equipment" or "scuba apparatus"—examples of the linguistic RAS syndrome. It has been adapted into the Welsh language as "sgwba".
[edit]Types of diving
Divemaster ready to dive Shark and Yolanda reefs at Rās Muhammad, Sharm el-Sheikh.
Scuba diving is still evolving, but general classifications have grown to describe various diving activities. These classifications include:
Commercial diving
Military diving
Naval diving
Police diving
Professional diving
Recreational diving
Rescue and recovery diving
Scientific diving
Technical diving
Cave diving
Cavern diving
Deep diving
Ice diving
Wreck diving
Reasons for diving may include:
Breathing underwater
The diver down flag - Designates a diver is in the water
For more information, see Diving regulator.
Water normally contains dissolved oxygen from which fish and other aquatic animals extract all their required oxygen as the water flows past their gills. Humans lack gills and do not otherwise have the capacity to breathe underwater unaided by external devices.[2]
Early diving experimenters quickly discovered it is not enough simply to supply air in order to breathe comfortably underwater. As one descends, in addition to the normal atmospheric pressure, water exerts increasing pressure on the chest and lungs — approximately 1 bar or 14.7 psi for every 33 feet or 10 meters of depth — so the pressure of the inhaled breath must almost exactly counter the surrounding or ambient pressure to inflate the lungs. It generally becomes difficult to breathe through a tube past three feet under the water.[2]
By always providing the breathing gas at ambient pressure, modern demand valve regulators ensure the diver can inhale and exhale naturally and virtually effortlessly, regardless of depth.
Because the diver's nose and eyes are covered by a diving mask; the diver cannot breathe in through the nose, except when wearing a full face diving mask. However, inhaling from a regulator's mouthpiece becomes second nature very quickly.
For the history of diving, see timeline of underwater technology.
Contents [hide]
1 History
2 Etymology
3 Types of diving
4 Physiological issues
4.1 Breathing underwater
4.2 Open-circuit
4.3 Rebreather
4.4 Gas mixtures
4.5 Injuries due to changes in air pressure
4.6 Effects of breathing high pressure gas
4.6.1 Decompression sickness
4.6.2 Nitrogen narcosis
4.6.3 Oxygen toxicity
4.7 Refraction and underwater vision
4.8 Controlling buoyancy underwater
4.9 Avoiding losing body heat
4.10 Avoiding skin cuts and grazes
4.11 Diving longer and deeper safely
4.12 Being mobile underwater
5 Scuba dive training and certification agencies
6 See also
7 Reference list
8 Further reading
9 External links
History
Scuba today typically refers to the in-line open-circuit equipment, developed by Emile Gagnan and Jacques-Yves Cousteau, in which compressed gas (usually air) is inhaled from a tank and then exhaled into the water. However, rebreathers (both semi-closed circuit and closed circuit) are also self-contained systems (as opposed to surface-supplied systems) and are therefore classified as scuba.
[edit]Etymology
The term SCUBA (an acronym for Self-Contained Underwater Breathing Apparatus) arose during World War II, and originally referred to United States combat frogmen's oxygen rebreathers, developed by Dr. Christian Lambertsen for underwater warfare.[2][3][4].
The word SCUBA began as an acronym, but it is now usually thought of as a regular word—scuba. It has become acceptable to refer to "scuba equipment" or "scuba apparatus"—examples of the linguistic RAS syndrome. It has been adapted into the Welsh language as "sgwba".
[edit]Types of diving
Divemaster ready to dive Shark and Yolanda reefs at Rās Muhammad, Sharm el-Sheikh.
Scuba diving is still evolving, but general classifications have grown to describe various diving activities. These classifications include:
Commercial diving
Military diving
Naval diving
Police diving
Professional diving
Recreational diving
Rescue and recovery diving
Scientific diving
Technical diving
Cave diving
Cavern diving
Deep diving
Ice diving
Wreck diving
Reasons for diving may include:
Breathing underwater
The diver down flag - Designates a diver is in the water
For more information, see Diving regulator.
Water normally contains dissolved oxygen from which fish and other aquatic animals extract all their required oxygen as the water flows past their gills. Humans lack gills and do not otherwise have the capacity to breathe underwater unaided by external devices.[2]
Early diving experimenters quickly discovered it is not enough simply to supply air in order to breathe comfortably underwater. As one descends, in addition to the normal atmospheric pressure, water exerts increasing pressure on the chest and lungs — approximately 1 bar or 14.7 psi for every 33 feet or 10 meters of depth — so the pressure of the inhaled breath must almost exactly counter the surrounding or ambient pressure to inflate the lungs. It generally becomes difficult to breathe through a tube past three feet under the water.[2]
By always providing the breathing gas at ambient pressure, modern demand valve regulators ensure the diver can inhale and exhale naturally and virtually effortlessly, regardless of depth.
Because the diver's nose and eyes are covered by a diving mask; the diver cannot breathe in through the nose, except when wearing a full face diving mask. However, inhaling from a regulator's mouthpiece becomes second nature very quickly.
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