The Balloon That Sank to the Deepest Point in the Ocean
In January 1960, Jacques Piccard and US Navy lieutenant Don Walsh sank almost 11 kilometers to the bottom of the Challenger Deep, the deepest point in the ocean. Their craft, the Trieste, was really a balloon built to sink: a float full of gasoline holding up a steel sphere, with tons of iron to drop on the way home. This is its story, told mostly from the book Opening the Great Depths by Norman Polmar and Lee Mathers.
In this independent explainer, I follow the Trieste from a balloon in the sky to the bottom of the sea.
In the video
- 1931: Swiss physicist Auguste Piccard rose about 15.8 kilometers in a sealed aluminum ball under a hydrogen balloon, higher than anyone had flown. A stray rope tangled the line that opens the gas valve, so he and his assistant waited for sunset to come down, onto a glacier in the Alps
- The idea: as a student, Piccard read about glowing fish hauled up from the deep. Back then, people went deep in a steel ball hanging from a ship on a cable. He wanted no cable at all, so he designed a balloon that sinks. A float of gasoline, which is lighter than water and hardly shrinks under pressure, holds up a thick steel sphere for the crew. The ballast is iron shot held on by electromagnets. Drop some to slow down or rise. If the power fails, it all drops and the craft floats up on its own
- 1948: his first bathyscaph, FNRS 2, made a test dive off West Africa with nobody aboard and came back up by itself. Then waves wrecked its float while it was under tow, and his Belgian backers dropped him
- 1953: his son Jacques found new backers in the city of Trieste. Father and son took the new craft down more than 3,000 meters, deeper than anyone had been. It was Auguste's last dive
- 1958: the US Navy bought the Trieste and gave it a stronger sphere from Krupp, three forged pieces glued together with epoxy. After a record dive off Guam, the glue failed and the middle ring slipped. A 60-ton jack pushed it back
- January 23, 1960: colder layers of water stopped the descent four times near the surface. A message from the Navy lab said "Cancel diving, come home." The reply: "Trieste now passing 20,000 feet." Near 10,000 meters, they felt a jolt and heard a crack. They kept going, and touched bottom at 35,800 feet, about 10,912 meters
- On the bottom: the crack was a window in the entry tube. If it had failed, they could have been trapped inside for days. Jacques said he saw a flatfish. That sighting is disputed: no fish has been found deeper than about 8,300 meters
- What came after: no one went back to the bottom of the Challenger Deep for 52 years. Deep subs today still carry steel weights they drop to come home
The book
"Opening the Great Depths: The Bathyscaph Trieste and Pioneers of Undersea Exploration"
Norman C. Polmar and Lee J. Mathers
Naval Institute Press, May 2021 (ISBN 978-1-68247-591-1)
The book goes much deeper than this video: the French Navy's rival bathyscaph, the people of the Navy's Project Nekton, and how the deepest dive was planned, run and nearly called off. If deep-sea exploration interests you, it's worth reading in full.
This is an independent explainer. I'm not affiliated with or endorsed by the authors or the Naval Institute Press. My company, Piccard, is named after Auguste and Jacques Piccard as inspiration, the way Tesla is named after Nikola Tesla. It has no connection to the Piccard family.
The animations are my own illustrations, not archival footage, and the maps and the pressure chart are schematic. The facts come from the book, checked against other sources, including Don Walsh's 1962 Navy report, Jacques Piccard's 1960 account, the Naval History and Heritage Command and Yancey et al. (PNAS, 2014). Any mistakes are mine.
I'm Bora Celik from Piccard. I explain new research in ocean science and robotics.