Buddy diving just before and after the Second World War. After the invention of the "aqualung" by Cousteau and Gagnan, the first commercially underwater breathing apparatus became available for sale for sporting purposes in the late 1940s. As the new sport of scuba diving rapidly expanded through the 1950s, several sporting organisations—notably the YMCA—began programmes to train swimming enthusiasts in this new aquatic pastime, and began to codify what they believed were proper practises for this expanding sport. The YMCA considered the buddy system a useful corollary to the "never swim alone" rule of their swimming and lifesaving programmes. Cousteau himself independently
Jacques Cousteau an aqualung, while attempting a new depth record with the GERS near Toulon. In 1948, between missions of mine clearance, underwater exploration and technological and physiological tests, Cousteau undertook a first campaign in the Mediterranean on board the sloop "Élie Monnier", with Philippe Tailliez, Frédéric Dumas, Jean Alinat and the scenario writer Marcel Ichac. The small team also undertook the exploration of the Roman wreck of Mahdia (Tunisia). It was the first underwater archaeology operation using autonomous diving, opening the way for scientific underwater archaeology. Cousteau and Marcel Ichac brought back from there the Carnets diving film (presented and preceded