SCUBA diving involves using a self-contained underwater breathing apparatus to explore underwater. The document discusses the history and development of SCUBA equipment from ancient times to modern regulators. It describes the basic gear used in SCUBA including masks, fins, buoyancy compensators, regulators, and wetsuits or drysuits. Various types of dives and safety considerations are covered, as well as statistics on certified divers worldwide and popular dive locations around the world and in the United States.