The machine was a steel ball the size of a small kitchen, hung beneath a tank of gasoline, and on the morning of 23 January 1960 two men sealed themselves inside it and began to sink into the deepest hole in the ocean. Above them, in the Pacific southwest of Guam, the sky was overcast and heavy seas were running twenty-five-foot swells; below them was the Challenger Deep, the bottom of the Mariana Trench, nearly seven miles straight down. For the next five hours they fell through water that grew blacker and colder the deeper it got, watching tiny luminous creatures stream past the porthole like an upside-down snowstorm.
Somewhere around 32,400 feet, a muffled bang went through the cabin and the whole vessel shook — as though, Walsh said, they were on land in a mild earthquake. They switched off the instruments and the telephone so they could listen. Nothing followed. Every gauge read normal. They had no idea what had made the noise. They looked at each other, shrugged, and kept going down.
To understand how a thing like that could exist — a vehicle that fell on purpose and came back — you have to start with the man who built it, and with the fact that he had spent the previous decade going the opposite direction.
The sphere that began in the sky
Auguste Piccard was a Swiss physicist with a long face and a longer reach. In May 1931 he and his assistant Paul Kipfer climbed into a sealed aluminum gondola, hung it under a hydrogen balloon, and rose to 15,781 meters — the first humans to reach the stratosphere. The trick that made it survivable was the gondola itself: a pressurized sphere that kept ordinary sea-level air around the crew while the near-vacuum outside tried to pull it apart. Hold the pressure difference, and a thin shell could protect a body in a place the body had no business being.
By the late 1930s Piccard had turned the idea over in his head and realized it ran both ways. A sphere strong enough to hold pressure in could just as well hold pressure out. The deep ocean was the stratosphere’s mirror: instead of nothing pressing from outside, there was everything — thousands of tons of water per square foot. The same pressurized cabin that had carried him toward space could carry a man toward the seafloor.
A balloon, turned inside out
The harder problem was buoyancy. A balloon floats in air because it is filled with a gas lighter than air. There is no gas you can put in a tank to float it in water, and a tank big enough to lift the heavy steel sphere would itself be crushed at depth. Piccard’s answer was to fill the float not with gas but with gasoline. Gasoline is lighter than water, so it lifts; and unlike air it barely compresses, so the sea could press on it as hard as it liked without squeezing it down to nothing. Hang the heavy crew sphere beneath a big thin-walled tank of gasoline, load the craft with iron shot for ballast, and you had a free vehicle that could descend by dropping a little weight and rise by dropping more. He called it a bathyscaphe — Greek for “deep boat.”
The vessel that made the dive was Piccard’s third design, named for the city where much of it was assembled. Its gasoline float was built in the Free Territory of Trieste; its pressure sphere was cast in Italy and the craft was assembled and launched near Naples, at Castellammare di Stabia, in the summer of 1953. Piccard was nearly seventy by then, and the man at the controls on the early dives was his son Jacques.
Bought by a navy
The Trieste spent its first years making deep dives in the Mediterranean, but the money to push it to the very bottom came from the United States. The U.S. Navy bought the bathyscaphe in 1958 for $250,000 and shipped it to San Diego. For the deepest dives the Navy ordered a stronger crew sphere from the Krupp works in Germany — a ball just over two meters across with walls five inches thick, weighing more than fourteen tons in air. Inside, two men could sit; barely.
The plan was called Project Nekton: a string of test dives in the Pacific near Guam, building toward a single attempt on the Challenger Deep itself. Jacques Piccard would pilot. The Navy assigned Lieutenant Don Walsh, a submarine officer, to ride with him — partly because someone from the service had to be aboard, and partly because Walsh had spent months learning the temperamental craft. The weather in late January 1960 never did give them a clean window; the tow out from Guam left the Trieste wallowing and awash. Piccard tested the circuits and the ballast magnets, found them sound, and decided they would go anyway. A message then arrived from San Diego ordering the dive cancelled. The project director let it sit in his pocket through a leisurely breakfast, then reported back that the Trieste was already thousands of feet down.
Seven miles down
They descended slowly, on purpose, averaging about a meter per second — what Piccard likened to the speed of an elderly elevator — and eased off further on the final approach, so that meeting the bottom unexpectedly would not wreck the craft. The float held some 34,000 gallons of gasoline; nine tons of iron shot waited in each of two hoppers, fore and aft of the crew sphere, held in place by electromagnets and ready to be dumped to slow the fall or start the climb. The magnets were the safeguard: lose electrical power and the shot would fall away by itself, and the Trieste would rise whether the crew were conscious or not.
They never did learn, on the way down, what had broken. There was no leak in the sphere and no falling pressure, and Walsh’s reasoning was blunt: had it been serious, the two of them would already have been, in his phrase, red mush. So they went on with the question unanswered and better than half a mile still beneath them. The pressure outside the sphere was climbing toward 16,000 pounds on every square inch, and inside it the temperature fell to about 7 degrees Celsius; the men changed into dry clothes in a space they could not stand up in, and waited.
Four hours and forty-seven minutes after leaving the surface, the Trieste settled onto the bottom at roughly 10,900 meters — about 35,800 feet, near enough to seven miles. As far as anyone knows, no one had ever been there. “We shook hands,” Walsh remembered, “and said, Well, we did it.”
The landing stirred up a cloud of pale silt off the floor, and the view through the porthole went, in Walsh’s words, like looking into a bowl of milk. As the ooze drifted past, Piccard reported seeing a flatfish — “apparently of the sole family,” he wrote, about a foot long — moving away across the bottom, which he took as proof that vertebrate life reached even here. Marine biologists have doubted it ever since; the chemistry that lets a fish’s cells work under pressure appears to give out somewhere around 8,200 meters, well short of the bottom. Walsh came round to their side, and went further than they had to. “We were two engineers, not biologists,” he said in a later interview. “What we probably saw was a Holothuria, a sea cucumber, an invertebrate” — a flattened animal that could pass for a sole in a cloud of silt. What is certain is the silt, the cold, and the milk-white window.
It was on the bottom, looking out the rear window, that Walsh finally found the bang. The big viewing port in the entrance tube above the sphere had cracked — not from pressure, since that tube flooded on every dive and carried the sea inside it, but from the metal around it shifting in the cold. The crack could not sink them. What it could do was trap them: if the pane shattered while they were blowing the tube dry at the surface, there would be no way out of the sphere until the Trieste was towed four days back to Guam and lifted from the water.
That settled how long they stayed. The silt was not clearing, the winter day above them was short, and they wanted daylight for the business with the window. Twenty minutes after landing — ten short of the planned half hour — they held up a Swiss flag and an American one for a camera bolted inside the sphere, and Piccard dropped two tons of iron. The Trieste lifted off, and the milk slowly cleared back to black. The climb took about three and a half hours. They surfaced into the Pacific swell at 4:56 in the afternoon, bled air into the tube until the water went down past the cracked pane without shattering it, and climbed out into ordinary air with their teeth chattering.
The bottom, left alone
The depth they reached has been measured and re-measured since, the figures nudging around as instruments improved, but the fact of it has not moved: two men in a gasoline-floated steel ball had touched the deepest point of the planet’s surface and come back. Walsh and Piccard came up assuming someone would be back within two or three years. Nobody was. There turned out to be no practical way to reload the Trieste with iron ballast at sea, which made a second run at the bottom a far larger undertaking than the first; and the Navy, citing safety, capped the craft at 6,000 meters — a little over half the depth it had just touched. The Trieste went back to shallower work out of San Diego, and within three years it was on the East Coast hunting the wreck of the submarine Thresher. The next generation of research submersibles, built by oceanographic institutions around the world, also stopped at about 6,000 meters. The Challenger Deep was reached, and then it was left alone.
No person went back for fifty-two years. Robots did — a Japanese probe in 1995, an American one in 2009 — but not until 2012 did anyone ride down to that floor again: the filmmaker James Cameron, descending alone in a submersible he had spent years helping to design. By then Auguste Piccard was long dead, and the principle he had pulled out of a balloon ride still held: to survive where the world presses hardest, you do not fight the pressure. You build something that can carry your own thin pocket of ordinary air down into it, and bring it back.