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 Émile Gagnan Émile Gagnan (November 1900 – 1979) was a French engineer and, in 1943, co-inventor with French Navy diver Jacques-Yves Cousteau of the Aqua-Lung, the diving regulator (a.k.a. demand-valve) used for the first Scuba equipment. The demand-valve, or regulator, was designed for regulating gas in gas-generator engines, but was found to be excellent for regulating air-supply under varied pressure conditions. This allowed people to explore the ocean more easily, even though the original purpose was different. Gagnan was born in the French province of Burgundy in November 1900, and graduated from technical school in the early 1920s. He was