Aqualung is a brand of scuba diving equipment, most notably the open-circuit self-contained underwater breathing apparatus (SCUBA) of the same name. The term 'Aqualung' was coined by Jacques Cousteau and Émile Gagnan, who developed the first successful open-circuit SCUBA in 1943. The Aqualung is a popular choice for recreational divers due to its ease of use and reliability. It is also used by professional divers and military personnel.