Plunging into the deep, dark abyss of the Pacific Ocean’s Mariana Trench, U.S. Navy Lt. Don Walsh and Swiss engineer Jacques Piccard heard a loud cracking sound in their vessel—the bathyscaphe Trieste, which the Office of Naval Research (ONR) purchased for scientific observations.

Already 30,000 ft. below sea level, Walsh and Piccard faced the ultimate decision—risk their lives to become the first people to travel to the deepest part of the ocean, the Challenger Deep, or return to safety.

The crack had scarred one of Trieste’s outer plexiglass panels, but Walsh and Piccard (whose father designed Trieste) decided to push on. After a nearly 5-hr. descent, the Trieste reached the Challenger Deep, approximately 36,000 ft. below sea level, on January 23, 1960.

Exactly 60 years later, on January 23, 2020, the National Museum of the U.S. Navy in Washington, D.C., celebrated the anniversary of Trieste’s journey with a program featuring Walsh, the lone remaining pilot of the trip.

“ONR is underappreciated for this whole enterprise,” Walsh said at the ceremony. “All credit is due to ONR—they were the ones that rolled the dice buying the Trieste from the Swiss.”

Learn more at www.onr.navy.mil/Media-Center/Press-Releases/2020/60th-Anniversary-Trieste-Dive and www.history.navy.mil/research/histories/ship-histories/danfs/t/trieste.html.