Hannes Keller (born 20 September 1934 in Winterthur, Switzerland) is a Swiss physicist, mathematician, deep diving pioneer, and entrepreneur. In 1962, he reached a depth of 1,000 feet (300 m) in open ocean. In the 1970s through the 1980s, Keller made himself a name as an entrepreneur in the IT industry. Keller is also an amateur classical pianist who produced two CDs and occasionally performed for audiences of up to 2000 people.
Keller 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. 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). On Dec. 3, 1962, 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. 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.
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. He developed a series of software products (Witchpen, Ways for Windows, and Wizardmaker) which provided automatic spell checking, literal machine translation, and macro recording.