Solo diving II. In the late 1940s, after the invention of the Aqua-lung by Cousteau and Gagnan, the first retail underwater breathing apparatus for sport was commercially marketed. As the sport expanded through the 1950s, several sporting organisations – notably the Young Men's Christian Association (YMCA) – began scuba training programmes for swimming enthusiasts, thus began the codification of what was believed to be proper practices for the expanding amateur sport of scuba diving. The buddy system was thought to be a useful corollary to the "never swim alone" edicts of the YMCA swimming and lifesaving programmes. Cousteau independently implemented a buddy
Aqua Lung/La Spirotechnique Aqua Lung/La Spirotechnique La Spirotechnique (now Aqua Lung International) is a large and well-known firm which makes scuba and other self-contained breathing apparatus, and other diving equipment. It produced the Aqua-Lung line of regulators, like the CG45 (1945) and the Mistral (1955), among others. Until 2016, the company was a division of Air Liquide since its foundation in 1946. The company was sold to Montagu Private Equity in 2016. In December 1942 the "lieutenant de vaisseau" (ship-of-the-Line Lieutenant) Jacques-Yves Cousteau met in Paris for the first time the engineer Émile Gagnan, employee at Air Liquide, a French company specialising in