Scuba Diving

Scuba diving is a form of underwater diving in which a diver uses a self-contained underwater breathing apparatus (scuba) to breathe underwater.Unlike other modes of diving, which rely either on breath-hold or on air pumped from the surface, scuba divers carry their own source of breathing gas, usually compressed air, allowing them greater freedom of movement than with an air line or diver's umbilical and longer underwater endurance than breath-hold. Scuba equipment may be open circuit, in which exhaled gas is expelled to the surroundings, or a closed or semi-closed circuit rebreather, in which the breathing gas is scrubbed to removecarbon dioxide, and the oxygen used is replenished from a supply of feed gas before being re-breathed.