In 1965, America trained astronauts for spaceflight with stints as aquanauts, spending 30 days living and working in habitats 205ft below the surface. What were their experiences like underwater? What was the nature of the facilities? Did their time underwater prove helpful for spaceflight?

Scott Carpenter took part in the SEALAB II program, but that was more of an individual pursuit. (At the time he was on leave from the astronaut corps.)

Carpenter was, at the time, in something of an odd position. His poor performance in Aurora 7 (MA-7) in 1962 had lead to him being (unofficially) grounded. A shoulder injury in 1964 lead him to being officially grounded, and eventually to being permanently removed from flight status in 1967.

He did go on to use his experience as a diver to help develop techniques for practicing spacewalks underwater to simulate zero-G. That practice continues today.