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
Aqua-Lung first book, "The Silent World", in 1953. Public use of the word "aqualung", and public interest in Aqualungs and scuba diving, were started around 1953 in English-speaking counties by a National Geographical Society Magazine article about Cousteau's underwater archaeological expedition to Grand Congloué. In France, aqualung diving was popularized by Cousteau's movie "Épaves", while his book "The Silent World" also helped significantly. As with some other registered trademarks, the term "aqualung" became a genericized trademark in English-speaking countries as a result of common use by the public and in publications, including the BSAC's official diving manuals. Presumably, lawyers for Cousteau