SCUBA stands for ‘Self Contained Underwater Breathing Apparatus’. Scuba diving is a form of underwater diving in which a diver uses a scuba set to breathe underwater.
Unlike early diving, which relied exclusively on air pumped from the surface, Modern scuba diving gear consists of one or more gas tanks strapped onto a diver’s back. These are connected to an air hose and a unique invention (in 1942 by Emile Gagnan and Jacques Cousteau) called a regulator. The regulator controls the airflow, so that the air pressure within the diver’s lungs equals the pressure of the water.
Scuba divers carry their own source of breathing gas (usually compressed air), allowing them greater freedom than with an air line.
Both surface supplied and scuba diving allow divers to stay underwater significantly longer than with breath-holding techniques as used in snorkeling and free-diving.
Depending on the purpose of the dive, a diver usually moves underwater by swim fins attached to the feet.