Hannes Keller (September 20, 1934 – December 1, 2022(2022-12-01) (aged 88)) was a Swiss physicist, mathematician, deep diving pioneer, and entrepreneur. In 1962, he reached a depth of 1,000 feet (300 m) in open ocean.^[1][2][3] In the 1970s through the 1980s, Keller made himself a name as an entrepreneur in the IT industry.^[4] Keller was also an amateur classical pianist who produced two CDs and occasionally performed for audiences of up to 2000 people.^[4][5][6]

Keller was born in Winterthur, Switzerland. He studied philosophy, mathematics, and theoretical physics at the University of Zurich. He became interested in deep diving and developed tables for mixed-gas decompression, supported by Albert A. Bühlmann who suggested suitable gases.^[1][4] Keller successfully tested his idea in Lake Zurich, where he reached a depth of 400 feet (120 m), and Lake Maggiore, where he reached a depth of 728 feet (222 m).^[8] On December 3, 1962,^[9] he set a new world record when he reached a depth of 1,000 feet (300 m) off the coast of Santa Catalina Island, California, together with Peter Small.^[7][10] This major achievement was overshadowed by the tragic end of the mission: Keller was lucky to survive while Peter Small and Chris Whittaker, a young UCLA student and supporting diver, lost their lives.^[11]

In the following years, navies and hospitals bought decompression chambers constructed by Keller.

In the 1970s, Keller sold his own line of computers and in the 1980s became a leading vendor of IBM PCs in Switzerland.^[4] He developed a series of software products (Witchpen, Ways for Windows, and Wizardmaker) which provided automatic spell checking, literal machine translation, and macro recording.

Keller used to run Visipix^[12] the largest fine art and photo museum online with 1.3 million exhibits, all with free copyrights for any use.^[4]

After 2005, Keller was a full-time artist.^[4]

In 2009, Keller joined the advisory board for the United States Historical Diving Society.^[13]

Keller died on 1 December 2022 in Niederglatt, Switzerland, at the age of 88.^[14]