The four ‘aquanauts’ of the 19th NASA Extreme Environment Mission Operations (NEEMO) from left:  Canadian astronaut Jeremy Hansen, ESA trainer Hervé Stevenin, ESA astronaut Andreas Mogensen and NASA astronaut astronaut Randy Bresnik.<br>
NASA’s underwater training missions are held off the coast of Florida and send astronauts 20 m below the sea to live in a makeshift space base where they conduct regular ‘waterwalks’ in scuba gear.
NASA/Mark Widick
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