Sullivan descended nearly 11 km to Challenger Deep aboard Limiting Factor, becoming the first woman there and first person to reach both space and the ocean's deepest point.
On June 7, 2020, Kathryn Sullivan descended aboard the deep-submergence vehicle Limiting Factor to the Challenger Deep, the deepest known point in Earth's oceans, located in the Mariana Trench nearly 11 kilometers (about 35,000 feet) beneath the surface of the Pacific Ocean.
With this dive, Sullivan became the first woman ever to reach Challenger Deep, and remarkably, the first person in history to have traveled both to outer space and to the deepest point of the ocean—an extraordinary distinction combining the extremes of human exploration, from the vacuum of space to the crushing pressures of the hadal zone.
The expedition was part of the Five Deeps Expedition-linked Ring of Fire program led by explorer Victor Vescovo, whose submersible technology enabled a new generation of deep-sea research. During the dive, Sullivan and her fellow crew conducted communications tests with the International Space Station, symbolically linking the two extremes of human exploration in a single moment.
This achievement, occurring shortly after the publication of her memoir reflecting on her life in science and space, drew significant global media attention and further cemented Sullivan's legacy as one of the most versatile and pioneering explorers of her generation—someone whose career uniquely bridged geology, oceanography, atmospheric science, and human spaceflight. Her Challenger Deep dive stands as a capstone achievement in a lifetime devoted to pushing the boundaries of exploration.