Hans Hass) was an Austrian biologist and underwater diving pioneer. He was known mainly for being among the first scientists to popularise coral reefs, stingrays and sharks. He pioneered the making of documentaries filmed underwater. He led development of the aqualung and of a type of rebreather. He is known, too, for his energon theory and his commitment to protecting the environment.

https://en.wikipedia.org/wiki/Hans_Hass