noun - An aquanaut is the marine equivalent of an astronaut. It is an individual who remains underwater in an underwater habitat on the seafloor for a period equal to or greater than 24 continuous hours without returning to the surface. The term is often restricted to scientists and academics, though there were a group of military aquanauts during the SEALAB program.
An aquanaut is distinct from a submariner, in that a submariner is confined to a moving underwater vehicle such as a submarine that holds the water pressure out.
Aquanaut derives from the Latin word aqua ("water") plus the Greek nautes ("sailor").
The first human aquanaut was Robert Sténuit, who lived on board a tiny one-man cylinder at 200 feet (61 meters) for 24 hours in September 1962 off Villefranche-sur-Mer on the French Riviera. Military aquanauts include Robert Sheats, Shorty Lyons, Mike Meisky, Robert Croft, Billie L. Coffman, George Dowling, Bill Tolbert, and Wally Jenkins, author Robin Cook, and astronauts Scott Carpenter and Alan Shepard. Civilian aquanaut Berry L. Cannon died of carbon dioxide poisoning during the U.S. Navy's SEALAB III project.
Scientific aquanauts include Richard Cooper, Stephen Neudecker, Al Waterfield, Jonathan Helfgott, Robert Dill, Sylvia Earle, Ian Koblick, Neil Monney, Chris Olstad, Joseph B. MacInnis, John Perry, Harold "Wes" Pratt (on whom the character Matt "Winch" Hooper in Jaws was based), Phillip Sharkey, Dick Rutkowski, Alina Szmant, Bill High, Phil Nuytten, Matthew Morgan, Steven Miller, Morgan Wells, C. Lavett Smith and about 700 others, including the crew members (many of them astronauts) of NASA's NEEMO missions at the Aquarius underwater laboratory.