1960

Trieste (bathyscaphe)

Piccard and Walsh make the first crewed descent to Challenger Deep

At about 32,400 feet they heard a crack. Their reasoning was brutally simple: if the pressure sphere had failed they would already be dead — so they kept descending.

23 January 1960, southwest of Guam

On 23 January 1960, U.S. Navy lieutenant Don Walsh and Swiss engineer Jacques Piccard descended in the bathyscaphe Trieste to the seafloor at Challenger Deep, the deepest known part of the world ocean. They were the first humans to reach it.

A Navy message had ordered the dive cancelled after Trieste launched. Project Nekton leader Andreas Rechnitzer delayed replying until he could truthfully report the craft was already thousands of feet down.

The Naval History and Heritage Command puts the descent at 4 hours 47 minutes.

Twenty minutes on the bottom

The shock and muffled noise at about 32,400 feet came from an acrylic viewing port in the free-flooded entrance trunk, not from the crew's sphere; they found it cracked once they were down.

They spent about 20 minutes on the seafloor, reached USS Wandank by acoustic telephone — a call that took roughly 30 seconds to draw a reply — released two tons of ballast and surfaced that afternoon.

The only food aboard was chocolate, eaten during an ascent in a cabin near 45°F.

The numbers that never settled

The onboard gauge read 37,800 feet, but it was miscalibrated. A NOAA-reviewed scientific history gives the calibrated direct measurement as 10,911 metres, or 35,797 feet; other accounts give 10,916 metres.

Timings vary too: the Naval Institute chronology gives an ascent of 3 hours 27 minutes, while museum accounts say about 3 hours 15.

Piccard reported seeing a sole-like flatfish. Subsequent biological evidence has not corroborated fish at that depth, and the sighting is now widely considered mistaken.

Sources

Researched 24 Aug 2026 6 sources not yet audited Date corrected

How this was checked

Researched from the web into a fact sheet and rewritten from that sheet. This article has not yet had an independent model audit. How the pipeline works →

Date corrected. The research places this at 1960-01-23.

What the sources leave uncertain

The date, participants and achievement are secure, but published depth figures vary because the onboard gauge was miscalibrated and later conversions and recalculations differ. A NOAA-reviewed scientific history gives the calibrated direct measurement as 10,911 meters.
Timings also vary slightly among reconstructions: Naval History and Heritage Command reports a 4-hour-47-minute descent, while a U.S. Naval Institute chronology gives an ascent of 3 hours 27 minutes; other museum accounts give about 3 hours 15 minutes.
Piccard reported seeing a sole-like flatfish, but subsequent biological evidence has not corroborated fish at that depth and the sighting is now widely considered mistaken.