This photograph of NASA astronaut Serena Aunon (@AstroSerena) moving tools and equipment underwater was taken during the NASA Extreme Environment Mission Operations (NEEMO) 20 mission, which began on July 20, 2015. NEEMO 20 is a 14-day mission by an international crew to the Aquarius Reef Base, located 62 feet (19 meters) below the surface of the Atlantic Ocean off the coast of Florida. NEEMO 20 is focusing on evaluating tools and techniques being tested for future spacewalks on a variety of surfaces and gravity levels ranging from asteroids to the moons of Mars and the Martian surface.