Hannes Keller Showed the World Humans Could Reach the Ocean’s Black Depths

Ever turn a cup upside down in the bath or a pool and dunk it below the surface? The cup bobs there, buoyed by a pocket of air trapped in the bottom of the cup. Push it slowly down and that air pocket remains—that’s what shoots the cup toward the surface when you let it go. That cup trick is essentially how a diving bell works. That relatively simple device has been around for centuries, likely since the first human noticed when a boat capsized and started to sink there was still air to breathe in the right pocket. Alexander the Great supposedly used one in one of his countless sieges.

Would you trust one to sink you to 1,000 feet of depth in the Pacific Ocean? Probably not.

Hannes Keller, a recreational diver, philosopher, inventor, and mathematician, sure did. And in doing so, on a tragic day in 1962, he set a record for deepest dive in human history at the time.

Okay, that’s not entirely fair. Keller used a closed bell for his dive, which is sealed to maintain ambient pressure as it sinks to eery, ink black depths. But the plain old diving bell is what piqued Keller’s interest to begin with, get this, a mere three years before he dove to the deepest depths anyone ever had.

Keller, born in Winterthur, Switzerland, in 1932, was teaching math in college when, in 1958, he started tinkering with diving in deep Swiss lakes. He learned of the diving bell principles, and built a rudimentary wooden helmet to act as the bell, with hoses to pump in oxygen. It barely worked, “Worked very bad,” Keller actually said. But his tinkerer’s brain was immediately fascinated with the complications of deep sea diving.

There is barely enough ‘air’ to breathe and it is bitter cold, even colder than the ice water in which we now hover. My teeth itch. I try to say okay but cannot manage it.

Keller reasoned that since space exploration required governmental assistance and financial resources unavailable to backyard diving enthusiasts, he could make his mark as an explorer by conquering new depths in the ocean.

He started working with a physiologist at the University of Zurich, Dr. Albert Buhlmann, experimenting with different gas mixtures to avoid nitrogen narcosis (a state similar to drunkenness caused by breathing gases under pressure) and the general problems associated with decompression sickness. The two tasked themselves with greatly shortening the time it took for a deep sea diver to decompress on the way to the surface. At the time, dives hundreds of feet down required sitting in a decompression chamber for twelve hours or more. Keller and Buhlmann wanted to go down to 700 feet and recover in an hour.

In 1961, Keller and journalist Ken MacLeish of Life Magazine plunged into the depths of Switzerland’s Lake Maggiore shooting for that mark, hoping a proprietary table of gases released at prescribed depths would keep the men safe. It worked, but it was miserable. At 328 feet, when they switched to a deepwater gas mixture to breathe, MacLeish reported:

“There is barely enough ‘air’ to breathe and it is bitter cold, even colder than the ice water in which we now hover. My teeth itch. I try to say okay but cannot manage it. Still, it appears that we can live on what we are getting.”

Motivated by that success, Keller decided to shoot for the moon. Or, rather, the deep depths of the ocean off the coast of Southern California. He decided he’d try to break the 1,000-foot barrier with the help of Buhlmann’s gas mixing tables. Might as well have been the moon at that depth.

December, 1962, Keller and another journalist, Peter Small, a diver with plenty of experience, were primarily concerned with the ascent and whether the gas blends concocted by Keller and Buhlmann (with the help of a hulking, rudimentary IBM computer crunching numbers) would prevent them getting the bends when they rose back to the surface.

“Anybody can go down,” Keller told Life Magazine about deepwater dives. Getting to the surface in one piece was the challenge. Keller and Small descended without incident to 1,000 feet, setting the record Keller had hoped for. But as he left the diving bell, the Atlantis, to sink Swiss and American flags on the bottom, his feet got tangled in his breathing hoses. Alarmed, he returned to the Atlantis but struggled to close the hatch. A TV camera monitored from above showed Keller and Small acting disoriented, then collapsing into unconsciousness as the Atlantis slowly rose to the surface. Two divers were sent to investigate and one was able to close the hatch, but the other diver simply vanished into the deep. His body was never found.

Small and Keller both came to during the ascent, but Small was deeply sickened. Before adequate medical help could be summoned, he died of the decompression sickness both men dreaded. It was assumed the gas blend was either miscalculated or somehow went bad.

Diving historian Christopher Swann told the New York Times, Keller’s dive “was a milepost in the sense that it was the first time something like that had been done.” But ultimately, Swann concluded, it had to be considered a failure because two divers lost their lives.

Yet Keller’s push to 1,000 feet opened eyes in the diving world, with the blend of nitrogen, oxygen, and helium the divers used showing what was possible. Saturation diving, which uses complex blends of gases that dissolve in a diver’s blood to match the ambient pressure of the environment, came along in the decade after Keller’s dive. That method allows divers to safely plunge to great depths and spend time working before returning to the surface to spend days decompressing. And at least one diver has passed the 1,000-foot mark swimming in modified SCUBA equipment.

Keller felt the ocean floor was the last great unexplored realm on the planet.

“If a man could go, for instance, to 1,000 feet down and do practical work,” Keller told The Sydney Morning Herald, “then all the continental shelf zone could be explored, a total of more than 16 million square miles.”

Keller went on to develop more deepwater diving equipment, then developed software. He died in 2022 at the age of 88.