and Lieutenant Don Walsh, USN. This was the first time a vessel, crewed or uncrewed, had reached the deepest point in the Earth's oceans. The onboard systems indicated a depth of 11521 m, although this was later revised to 10916 m and more accurate measurements made in 1995 have found the Challenger Deep to be slightly shallower, at 10911 m.

The descent to the ocean floor took 4 hours and 48 minutes at a descent rate of 0.914 m/s. After passing 9000 m one of the outer Plexiglas window panes cracked,