In 1984, NASA astronaut Kathy Sullivan made history as the first American woman to walk in space. Now, 36 years later, Sullivan has made history again as the first woman to travel to the deepest part of the ocean floor.

After completing her trip Monday, Sullivan is now the first person ever to both walk in space and make the 35,810-foot descent to Challenger Deep, the lowest part of the Marianas Trench, as Heather Murphy reports for the New York Times. According to a statement from EYOS Expeditions, the company who operates the submersible Sullivan traveled in, she has become just the eighth person ever to travel to Challenger Deep.

In 1984, NASA astronaut Kathy Sullivan made history as the first American woman to walk in space. Now, 36 years later, Sullivan has made history again as the first woman to travel to the deepest part of the ocean floor.

After completing her trip Monday, Sullivan is now the first person ever to both walk in space and make the 35,810-foot descent to Challenger Deep, the lowest part of the Marianas Trench, as Heather Murphy reports for the New York Times. According to a statement from EYOS Expeditions, the company who operates the submersible Sullivan traveled in, she has become just the eighth person ever to travel to Challenger Deep.

The 68-year-old former astronaut descended with explorer Victor Vescovo, who funded the expedition, in a submersible named Limiting Factor. The specially designed submersible can withstand 2,425 tons of pressure on its titanium hull. Limiting Factor is the first vehicle that has repeatedly gone to the bottom of the ocean, according to EYOS.

Located about 200 miles southwest of Guam, the Challenger Deep is a muddy depression in the Marianas Trench that reaches seven miles below the ocean’s surface. Sullivan and Vescovo spent about an hour and a half at the bottom capturing images from the submarine, and then embarked on the four-hour-long ascent.

When they resurfaced, the pair made a call to the International Space Station, which was flying more than 200 miles overhead—another first, as Doha Madani reports for NBC News.

“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,” Sullivan says in a statement.

“We made some more history today… and then got to share the experience with kindred spirits in the ISS,” Vescovo says in the statement. “It was a pleasure to have Kathy along both as an oceanographer during the dive, and then as an astronaut to talk to the ISS.”

Sullivan, who comlpeted three shuttle missions to space, has also conducted multiple oceanographic expeditions, according to her biography on NASA's website. She has previously served as the administrator of the National Oceanic and Atmospheric Administration and was inducted into the Astronaut Hall of Fame in 2004.

Following in Sullivan's footsteps, astronauts Christina Koch and Jessica Meir completed the first-ever all-female spacewalk last October, as Andrea Michelson reported for Smithsonian magazine at the time.