Scuba<unk> 
See Scuba<unk>  emergencies
Underwater<unk>  with the use of a compressed air cylinder, a regulator, a buoyancy compensator, and additional gear that generally includes a wetsuit, fins, mask, dive watch, weights.
Requires certification, generally through PADI or NAUI
Divers Alert Network, DAN emergency hotline phone number (919) 684-9111
See Scuba<unk>  emergencies
Underwater<unk>  with the use of a compressed air cylinder, a regulator, a buoyancy compensator, and additional gear that generally includes a wetsuit, fins, mask, dive watch, weights.
Requires certification, generally through PADI or NAUI
Divers Alert Network, DAN emergency hotline phone number (919) 684-9111
Free<unk> 
Underwater<unk>  without supplemental oxygen, dating back thousands of years to early shellfish divers. Additional gear may include weights, fins, suit, dive watch.
Competitive extreme sport, with several sub-categories. Deepest "no limits" depth records for males (214m, 702ft), females (160m, 525ft)
Underwater<unk>  without supplemental oxygen, dating back thousands of years to early shellfish divers. Additional gear may include weights, fins, suit, dive watch.
Competitive extreme sport, with several sub-categories. Deepest "no limits" depth records for males (214m, 702ft), females (160m, 525ft)
Snorkeling
Usually surface or shallow water swimming with the use of a snorkel to allow continuous breathing while the face remains submerged. Often used in resorts or tropical areas.
Usually surface or shallow water swimming with the use of a snorkel to allow continuous breathing while the face remains submerged. Often used in resorts or tropical areas.
Rebreather<unk> 
Tethered<unk> 
Surface supplied gas supplied by a hose from a source or a<unk>  bell.
Most often used in commercial or military<unk> , often in settings with little to no visibility.
Surface supplied gas supplied by a hose from a source or a<unk>  bell.
Most often used in commercial or military<unk> , often in settings with little to no visibility.
Pascals Law applies to the<unk>  body (without air filled areas such as lungs) states that the pressure applied to any part of the enclosed liquid will be transmitted equally in all directions through the liquid.
Boyles Law applies to the<unk>  body's air filled areas such as lungs, sinuses, middle ear, and states that the volume and pressure of a gas at a given temperature are inversely related.
At 2 ATA (10m/33ft) a given gas would be 1/2 it's volume, at 3 ATA (20m/66ft) it would be 1/3 it's volume and so on.
At 2 ATA (10m/33ft) a given gas would be 1/2 it's volume, at 3 ATA (20m/66ft) it would be 1/3 it's volume and so on.
Diving medicine
Barotrauma of descent
Poison control
Otic barotrauma
Blister chemical agents
Pulmonary barotrauma
Water purification
Sinus barotrauma