On what date did Trieste reach Challenger Deep?

Trieste reached Challenger Deep on 23 January 1960. The historic bathyscaphe carried U.S. Navy lieutenant Don Walsh and Swiss oceanographer Jacques Piccard to the floor of the Mariana Trench.

The descent was part of Project Nekton, a U.S. Navy programme of increasingly deep dives near Guam. Trieste took about four hours and 47 minutes to descend. After reaching the bottom, Piccard and Walsh remained there for roughly 20 minutes before beginning their ascent. The vessel’s instruments initially indicated a depth of 11,521 metres, but that figure was later revised to about 10,916 metres.

This date is sometimes confused with later Challenger Deep descents. James Cameron made a solo dive in 2012, while Victor Vescovo reached the bottom repeatedly in 2019. Those later achievements used newer submersibles and mapping technology, but Trieste’s 1960 dive remains the first crewed descent to the deepest known point in Earth’s oceans.