In 1962, Swiss physicist and deep-sea diving pioneer Hannes Keller embarked on an ambitious and perilous mission to push the boundaries of human endurance and underwater exploration. California, with its dramatic coastline and history of daring maritime ventures, became the setting for this bold effort to make history in diving. Partnered with British diver and journalist Peter Small, Keller aimed to descend to an unprecedented depth of 1,000 feet off the coast of Catalina Island. What promised to be a groundbreaking achievement, however, took a tragic turn.

Keller’s passion for deep-sea diving had recently garnered international attention, fueled by his record-breaking dives and groundbreaking research into advanced breathing gas mixtures. Working alongside Dr. Albert Bühlmann, a renowned physiologist specializing in respiration, Keller employed cutting-edge technology, including an IBM computer, to meticulously design gas formulas that could counteract the dangers of deep diving. Their innovative work addressed the twin challenges of nitrogen narcosis and decompression sickness, promising to revolutionize underwater exploration.

For Keller, diving was initially an unconventional pursuit. He was engaged in teaching mathematics to engineering students in his native town of Winterthur, close to Zurich, and had aspirations to become a pilot. However, the prohibitive cost of flying on a teacher’s salary led him to explore other avenues. Introduced to the burgeoning sport of scuba diving by a friend in the late 1950s, Keller applied his mathematical and scientific acumen to the field. He soon concluded that the existing techniques in deep-sea diving were outdated and ripe for revolutionary advancement.

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

Keller and Bühlmann worked collaboratively to expand their computerized concoction of breathing gases, ultimately selecting a dive site off near Avalon Bay at Catalina Island in Southern California. This location was chosen due to its dramatic underwater geography, where the ocean floor descends sharply from the coast into the deep ocean.

At the time, it was widely believed that no human being could safely dive to depths beyond three hundred feet. That was because, beginning at a depth of one hundred feet, a diver breathing normal air starts to lose his mind due to nitrogen narcosis.

Partnering with Peter Small, co-founder of the British Sub Aqua Club, Hannes Keller planned their historic descent using a specially designed diving bell named Atlantis. This advanced pressurized chamber, deployed from a surface support vessel, was staffed by a skilled technical crew tasked with monitoring gas levels and maintaining constant communication with the divers through a surface-to-bell phone link. The Atlantis diving bell represented a significant leap in underwater technology, providing a controlled environment that allowed divers to venture into previously unreachable depths. Its design and operational success revolutionized the field of deep-sea exploration, offering invaluable insights into human physiology under extreme pressure and laying the groundwork for future advancements in underwater science and technology.

Keller’s experimental dives piqued the interest of the U.S. Navy, as they saw the potential to revolutionize diving safety and practicality. If proven successful, Keller’s methods could transform existing dive tables and enable safer, more practical deep-sea exploration. Encouraged by the promising outcomes of Keller’s preliminary chamber tests and several less extreme open-sea trials, the Navy allowed him to perform a test dive at their primary experimental facility, adjacent to the Washington dive school. They also became a financial supporter of Keller’s ambitious thousand-foot dive.

To carefully scrutinize the operation, the Navy designated Dr. Robert Workman, one of their foremost decompression specialists, to be present on site. A few days after reaching Catalina in late November, Dr. Workman joined Dr. Bühlmann, the rest of Keller’s team, and various onlookers aboard Eureka, an experimental offshore drilling vessel provided by Shell Oil Co. Shell, like other oil and gas enterprises, had a vested interest in innovative techniques that could enhance the productivity of commercial divers. If the dive was successful, the company would receive Keller’s secret air mixture technology and thereby become an instant frontrunner in offshore oil exploration. Their interest was particularly relevant as offshore drilling initiatives were venturing into deeper waters, both off the California shore and in the Gulf of Mexico.

Resembling a huge can of soup, Atlantis stood seven feet tall and had a diameter slightly greater than four feet. Its structure featured an access hatch at the bottom and was adorned with an array of protruding pipes and valves, adding to its industrial appearance.

As a journalist, Peter Small intended to pen a first-hand narrative of the groundbreaking dive. On December 1, as part of a final preparatory dive, Small and Keller were lowered inside Atlantis to a depth of three hundred feet, where they spent an hour scuba diving outside the bell. During the decompression process within the bell, both divers experienced relatively mild symptoms of decompression sickness, commonly known as the bends. Keller felt the effects in his belly, while Small was afflicted in his right arm. Decompression sickness is still a relatively poorly understood phenomenon, and it remains unpredictable as to which part of the body it might affect.

Keller’s symptoms abated on their own that night, but Small’s discomfort lingered until he underwent recompression treatment. Despite this warning sign, Keller was determined to continue with the dive as planned, without conducting further incremental tests at increasing depths before the ambitious thousand-foot descent. His decision was likely influenced, at least in part, by the assembled crowd of journalists and other spectators eager to witness the historic dive. The constraints of time, finances, and equipment availability added to the pressure, compelling the team to proceed with the experimental dive as scheduled.

On Monday, December 3, around noon, Atlantis began its descent beneath the surface of the Pacific, enclosing its two divers within. The journey towards the ocean floor took under thirty minutes. Upon reaching the target depth of a thousand feet, a series of dark and chaotic moments ensued. Keller exited the bell to plant a Swiss flag and an American flag on the ocean floor. In the process, his breathing hoses became entangled with the flags, and after clambering back inside Atlantis, he lost consciousness.

The gas mixture had somehow become compromised. Peter Small also blacked out, despite never having left the diving bell. As Atlantis was hastily ascended to within two hundred feet of the surface, several support divers swam down to meet the bell. Tragically, one of these support divers, Christopher Whittaker, a young man of just nineteen, disappeared without a trace.

Keller came to roughly a half-hour after the incident, and Small regained consciousness, but it took nearly two hours for him to do so. Upon awakening, Small engaged Keller in coherent questions about what had transpired. He reported feeling cold and, although he retained the ability to speak, see, and hear, he could not feel his legs. Despite not experiencing any pain, he was too weak to stand. Leaning against his Swiss counterpart, he drifted off to sleep as their decompression within the bell continued.

Several hours later, as Atlantis was being transported back to shore to Long Beach from the dive site near Catalina, Keller discovered that Small had ceased breathing and had no pulse. Desperate to revive him, Keller administered mouth-to-mouth resuscitation and cardiac massage, but to no avail. Small was cold and pallid. The remaining pressure inside the bell, about two atmospheres, was hastily released in a frantic effort to get Small to a hospital after being trapped inside Atlantis for eight hours. Tragically, upon arrival, he was promptly pronounced dead.

The Los Angeles County coroner identified the cause of death as decompression sickness. An examination revealed that Small’s tissues and organs were filled with Nitrogen gas bubbles. However, Keller contended that other factors, such as a potential heart attack and the panic Small displayed upon reaching the thousand-foot mark, contributed to the tragedy.

Regardless of the underlying causes, the catastrophic dive to thirty atmospheres and the loss of two lives led to a rapid waning of interest in Keller’s previously sensational methods. The potential for failure of this magnitude had been a concern to many in the deep diving community and the day’s events set back research in the emerging field of saturation diving. Even before this event, saturation diving had only tepid support from the Navy, but this made some people loss faith in the technique. Of course, it would not be the end of saturation diving, not by a long shot. 

Modern deep-water diving owes much to the groundbreaking experiments of Hannes Keller. His historic dive to 1,020 feet (311 meters) off Catalina Island was a remarkable achievement that captivated the world. Far from being a mere stunt, as some critics claimed, Keller’s dive was a meticulously planned scientific endeavor designed to push the boundaries of human exploration of the ocean depths. This Swiss adventurer’s pioneering work laid the foundation for advances in deep-sea diving techniques, leaving an enduring legacy in the field.

Christopher Swann, a diving historian, said the dive “was a milepost in the sense that it was the first time something like that had been done.”

Keller ended up living a rich and long life, dying on December 1, 2022, at at a nursing home in Wallisellen, Switzerland, near his home in Niederglatt. He was 88.