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
Émile Gagnan employed as an engineer specializing in high-pressure pneumatic design by the large gas-supply firm Air Liquide. The first production 'Scaphandre Autonome' - or 'Aqualung' was released in France in 1946 under the identification code "CG45" ("C" for Cousteau, "G" for Gagnan and "45" for 1945, year of the patent). A year later, in 1947, Émile Gagnan and his family emigrated to Montreal, Quebec, Canada and he transferred to the employ of Canadian Liquid Air Ltd. There he set up a lab and proceeded to engineer, design, prototype and patent a very large number of SCUBA and undersea technology firsts, including