Jacques-Yves Cousteau was a pioneering diver, inventor of diving gear, and marine conservationist. His most important invention was the open-circuit scuba gear, which is the breathing system still used in most underwater diving today.
He explored the worlds oceans and fought to protect them, including preventing the dumping of nuclear waste. The song "Hi Calypso" honors him and his boat, the calypso.
He is probably one of the two most important figures in underwater exploration, along with Robert Ballard. To learn more, read http://en.wikipedia.org/wiki/Jacques_cousteau