First Female NASA Astronaut to Walk in Space Becomes First Woman to Reach Deepest Point in Earth's Oceans

Former NASA astronaut Kathryn Sullivan has become the first woman to reach the deepest known point in Earth's oceans, the Challenger Deep, which lies around 6.8 miles, or 36,000 feet, below the surface of the Pacific Ocean.

The 68-year-old, who was the first American woman to walk in space, emerged from her submersible Limiting Factor on Sunday following successful completion of her dive to the Deep, which lies at the bottom of Mariana Trench in the western Pacific—the deepest oceanic trench on Earth.

Sullivan and Limiting Factor's chief pilot, Victor Vescovo—a 54-year-old explorer, private equity investor and retired U.S. navy officer—began the dive on Saturday after the submersible was lowered into the water above the trench from the expedition ship.

The dive was part of a six-month Ring of Fire expedition operated by private companies EYOS Expeditions and Caladan Oceanic, The Times reported.

Sullivan, who also once served as the administrator of the National Oceanic and Atmospheric Administration (NOAA), became only the eighth person in history to reach Challenger Deep.

The first people to achieve the feat were Swiss oceanographer Jacques Piccard and U.S. Navy lieutenant Don Walsh in 1960. The pair were followed by film director James Cameron who made a solo dive in 2012 aboard the submersible Deepsea Challenger.

Then last year Limiting Factor made four trips to Challenger Deep in the space of eight days as part of EYOS and Caladan's Five Deeps Expedition. Vescovo piloted two of these dives, becoming the first person to have reached the summit of Everest, the two poles, and the bottom of four of the world's oceans.

The remaining three people to have reached Challenger Deep include Alan Jamieson, who was Chief Scientist on the Five Deeps Expedition, as well as Patrick Lahey and John Ramsay from Triton Submarines, the company that built Limiting Factor.

The latest descent to Challenger Deep took over four hours, with the total duration of the dive approaching 14 hours.

Sullivan is no stranger to exploration. She was a crew member on three Space Shuttle missions, and became the first American woman to walk in space on October 11, 1984.

Once Sullivan and Vescovo completed the dive, they celebrated their achievement by making a phone call to the International Space Station, which orbits the Earth at an altitude of around 250 miles.

"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 'spacecraft,'" Sullivan said Sunday.

Kathryn Sullivan
Kathryn Sullivan attends 18th Annual Webby Awards on May 19, 2014 in New York, United States. Brad Barket/Getty Images