Mr. Keller’s death was announced in a statement by his family. No reason was given.
The dive off Santa Catalina Island in California on December 3, 1962 to 311 meters was seen as an important step in experiments trying to overcome decompression sickness known as “the bends”, a potentially fatal condition caused by inert bubbles. gas such as nitrogen that forms in the divers’ bloodstream during rapid ascent from the depths.
Mr. Keller used a new cocktail of gases intended to reduce the risk of the turns. The formula was never made public, but it is credited with contributing critical data toward the development of the current mixture—nitrogen, oxygen, and helium—used in different proportions depending on the depth of the dive and other factors.
Mr. Keller’s diving companion, Peter Small, a British journalist and co-founder of the British Sub Aqua Club, did not survive the ascent in the cylindrical Atlantis diving bell due to decompression complications. Mr. Keller fell unconscious during the ascent and was near death.
One of the backup divers on the support ship Eureka, Chris Whittaker, a 19-year-old from Britain studying at the University of California at Los Angeles, also died while trying to rescue them. Whittaker’s body was never found.
Mr. Keller’s record “saturation dive,” as it is known to divers, also led to major scientific and technological advances, including improvements to deep-sea diving suits. Saturation diving remains below the surface for periods long enough to bring the body’s tissues into equilibrium with the partial pressure of the inert components of the breathing gas.
Mr. Keller’s later research on decompression chambers brought improvements to naval medical facilities in the United States and Great Britain.
His depth record lasted until 1975. The current record for a saturation dive was set by divers from the French unit Compagnie Maritime d’Expertises with their Hydra V111 watch, which reached a depth of nearly 1,751 feet in the Mediterranean Sea in 1988. (The Scuba). dive depth record of 1,090 feet was set by Egyptian Ahmed Gabr in the Red Sea in 2014, when he spent 12 minutes diving but nearly 15 hours returning to the surface to compensate for decompression).
Part of the preparation for Mr. Keller’s historic dive was done at a high-pressure laboratory tank operated by the Navy Experimental Diving Unit at the Washington Navy Yard on the Anacostia River.
After reaching the continental shelf off the California coast, Mr. Keller slipped through a hatch in the diving bell to plant Swiss and American flags. But the flags got caught in his breathing apparatus and he barely made it safely back into the watch.
Shell Oil financed the expedition and in return gained access to his then-secret technology, particularly his “cocktail” of gases to reduce decompression sickness, which helped make the company a leader in offshore oil exploration.
Because of the two deaths during the dive, some American media called Mr. Keller “Hanne’s Killer” and criticized him for not sharing details of his secret gas mixture with the wider scientific community.
Hannes Keller was born in Winterthur, near Zurich, on September 20, 1934. He studied philosophy, mathematics and theoretical physics at the University of Zurich, where he met Albert Bühlmann, a Swiss doctor who developed ways to reduce divers’ risk of decompression sickness by mixing gases .
Fascinated by diving since his youth, Mr. Keller first tested the techniques in a submersible dive in Lake Zurich, where he reached a depth of 400 feet, and later in Lago Maggiore on the Swiss-Italian border, down to 728 feet.
After the record-breaking dive, Mr. Keller went on to develop underwater suits, watches and other equipment, before entering the emerging computer industry in the 1970s. In 1975, he built and sold his own line of computers, called Sesame.
He also developed his own software products, including among the first programs to provide automatic spell checking and language translation. For a time he also ran an online photo and art museum and developed a Swiss-made watch called Nautical.
With a wicked sense of humor, in the 1970s he created a mechanical sea monster, based on Loch Ness’s fabled Nessie, which appeared in Lake Urnersee in Switzerland to amuse or sometimes frighten tourists. He called it Urnie.
In retirement he returned to another of his first loves, classical music, and became an amateur concert pianist, performing in Switzerland, Austria, Germany and the United States, where he was once a soloist under the renowned conductor Zubin Mehta.
In 2009, Mr. Keller was appointed to the advisory board of the Santa Barbara, California-based Historical Diving Society USA.
Complete information on survivors was not immediately available.
Writing in Diver Magazine in 2008, Hillary Hauser, an American photojournalist and prominent deep-sea diver, described Mr. Keller as “a person with a singular determination to live life to the fullest, at the risk of failure and even death.”
“Keller said to me once, ‘I want an interesting life, that’s what I want,'” added Hauser, whose husband, Dick Anderson, was the surviving rescue diver during Mr. Heller and Small’s record-breaking dive. “‘I’m the man looking for the right mix of all things to get me into the depths of life…so in the end I can say it was worth it.’