Scuba Diving

Scuba diving is a form of underwater diving in which a diver uses a scuba set to breath for recreation, commercial , or industrial reasons.

Unlike early diving ,which relied exclusively on air pumped from surface ,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.

According to the purpose of the dive, a diver usually moves underwater by swimfirns attached to the feet ,but external propulsion can come from an underwater vehicle, or a sled .

Source: Wikipedia