The first American woman to walk in space has become the first woman to reach the deepest known spot in the ocean.
On Sunday, Kathy Sullivan, 68, an astronaut and oceanographer, emerged from her 35,810-foot dive to the Challenger Deep, according to EYOS Expeditions, a company coordinating the logistics of the mission.
This also makes Dr. Sullivan the first person to both walk in space and to descend to the deepest point in the ocean. The Challenger Deep is the lowest of the many seabed recesses that crisscross the globe.
Dr. Sullivan and Victor L. Vescovo, an explorer funding the mission, spent about an hour and a half at their destination, nearly seven miles down in a muddy depression in the Mariana Trench, which is about 200 miles southwest of Guam.
After capturing images from the Limiting Factor, a specially designed deep-sea research submersible, they began the roughly four-hour ascent.
Upon returning to their ship, the pair called a group of astronauts aboard the International Space Station, around 254 miles above earth.
“As a hybrid oceanographer and astronaut this was an extraordinary day, a once in a lifetime day, seeing the moonscape of the Challenger Deep and then comparing notes with my colleagues on the ISS about our remarkable reusable inner-space outer-spacecraft,” Dr. Sullivan said in a statement released by EYOS Expeditions on Monday.
Early Sunday, Mr. Vescovo applauded Dr. Sullivan for being “the first woman to the bottom of the ocean.”
“That is really great,” Dr. Sullivan said after she floated into the cargo bay of the shuttle Challenger, about 140 miles above Earth.
She later became the administrator of the National Oceanic and Atmospheric Administration. Dr. Sullivan had a longstanding fascination with the ocean — before becoming an astronaut, she participated in one of the first attempts to use a submersible to study the volcanic processes that make the ocean crust, according to Collect Space, a space history site.
Tim Shank, a biologist at the Woods Hole Oceanographic Institution, called Dr. Sullivan a “consummate leader” in the study of the world’s oceans. There is currently only one submarine in the world that can reach the Challenger Deep, he said.
“I’m thrilled to hear that she was in it,” he said. “Anytime we can reach such extreme places on Earth to learn about them, it’s a major event.”
The Challenger Deep was discovered by the H.M.S. Challenger, a British ship that sailed the globe from 1872 to 1876. Since then, many expeditions have sought to measure the fissure’s depth, prompting disagreements not only about the precise figures but also over who truly was the first to reach the deepest point.
In April 2019, Mr. Vescovo, Dr. Sullivan’s diving partner, said he was; the “Titanic” director James Cameron disagreed, insisting he had gone deeper in 2012.
Dr. Sullivan will remain at sea for the next few days, according to a representative from Caladan Oceanic, another company involved in the mission.