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
Diving regulator which gained widespread acceptance. This came about after French naval officer Jacques-Yves Cousteau and engineer Émile Gagnan met for the first time in Paris. Gagnan, employed at Air Liquide, had miniaturized and adapted a Rouquayrol-Denayrouze regulator used for gas generators following severe fuel restrictions due to the German occupation of France; Cousteau suggested it be adapted for diving, which in 1864 was its original purpose. The single hose regulator, with a mouth held demand valve supplied with intermediate pressure gas from the cylinder valve mounted first stage, was invented by Australian Ted Eldred in the early 1950s in response to