Victor Vescovo—a renowned undersea explorer and former Naval officer, and Dr. Kathy Sullivan—an oceanographer and retired astronaut, just traveled 35,000 feet below the ocean’s surface.

This makes Sullivan, 68, the first person to both walk in space and descend to the deepest point in the ocean, known as the Challenger Deep, which is located about 200 miles southwest of Guam, The New York Times reports.