Retired U.S. Navy Capt. Don Walsh, best known for his daring dive to the deepest spot on Earth, nearly 36,000 feet below the ocean’s surface, has died at age 92.

Walsh was a co-pilot of the Trieste bathyscaphe, a deep submergence vehicle acquired by the Office of Naval Research (ONR) in 1958. Two years later, on January 23, 1960, Walsh and Swiss engineer Jacques Piccard, son of the inventor of the bathyscaphe, became the first humans to descend into the Challenger Deep, located in the Pacific Ocean’s Mariana Trench.

“ONR sponsored the Trieste, but it was then-Lt. Don Walsh who made the very daring decision to make the first descent into the deepest spot of the earth’s ocean. Walsh was a Navy officer, a submariner, an adventurer, and an oceanographer. To his family, we extend our deepest condolences and gratitude for allowing him to explore, and share his extraordinary experiences and knowledge with us,” said Chief of Naval Research Rear Adm. Kurt Rothenhaus.

Years later, Walsh described his dive with Piccard in a 2016 Future Force interview as “a pretty big deal” and a big relief to Adm. Arleigh Burke, who had greenlighted the expedition.

“Because he’d rolled the dice with us, just like ONR rolled the dice with us. He figured …they could probably do it. And we did it. And so he was pretty happy about that,” said Walsh.

Walsh’s journey to the Challenger Deep is still believed to hold the record for deepest dive yet in a manned vehicle, and ushered in a “golden age” of manned underwater exploration in the 1960s and 70s. Walsh and Piccard, though, saw little when they hit the ocean floor. They only had 20 minutes to survey their surroundings, which had become a cloud of debris, before heading back to the surface.

Walsh was a submariner, explorer and oceanographer, who also taught at the University of Southern California. His love of the ocean and advocacy for its exploration continued well after his Navy retirement in 1975.

In 2010, the U.S. Navy presented its highest civilian recognition, the Navy Distinguished Public Service Award, to Walsh for his achievement and service in the years following his Navy career. He had served as a U.S. policy adviser on State Department and federal science boards, authored more than 200 published contributions to marine literature and presented more than 1,500 lectures in 50 countries.