NASA Extreme Environment Mission Operations -- NEEMO
Where on Earth can an astronaut train in a spacelike environment? How about underwater? NEEMO is a project that sends groups of astronauts, engineers, doctors and professional divers to live in an underwater habitat for up to three weeks at a time.
NEEMO -- the NASA Extreme Environment Mission Operations project -- sends groups of NASA employees and contractors to live in Aquarius for up to three weeks at a time. For NASA, Aquarius provides a convincing analog to space exploration, and NEEMO crew members do some of the same tasks and face the same challenges underwater as they would in space.