Altitude diving
At altitude, atmospheric pressure is lower than at sea level, so surfacing at the end of an altitude dive leads to a greater relative reduction in pressure and an increased risk of decompression sickness compared to the same dive profile at sea level.
[7] The dives are also typically carried out in freshwater at altitude so it has a lower density than seawater used for calculation of decompression tables.
[10][11][12][13] Hennessy formulated that it was possible to convert standard air decompression tables for no-stop diving at altitude or from a habitat based on phase equilibration theory.
[14] Albert A. Bühlmann recognized the problem[15][16][17] and proposed a method which calculated maximum nitrogen loading in the tissues at a particular ambient pressure.
[27] In 2007, a new record was set in the small lagoon located near the summit of Pili Volcano, at just over 5,950 metres (19,520 ft), by Philippe Reuter, Claudia Henríquez and Alain Meyes.
[30][25] The current record for the highest scuba dive was set on December 13, 2019 by Polish diver and mountaineer Marcel Korkus.
The dive took place in the so-called basin (a natural water reservoir, which in terms of dimensions cannot be considered a lake).
[31][32][33][34] The highest scuba dive in the continental United States was done on 7 September 2013 by John Bali at Colorado's Pacific Tarn Lake, altitude 4,090 metres (13,420 ft).
[35][a] The deepest known staged decompression altitude dive was conducted by Nuno Gomes at Boesmansgat (Bushman's hole) in South Africa.
[37] Gomes's decompression schedule was calculated as being equivalent to a dive to 339 metres (1,112 ft) if it had been conducted at sea level.
In 1968 Jacques Cousteau mounted an expedition to explore Bolivia and Peru's Lake Titicaca in search of submerged Inca treasure.
The expedition departed from Matarani, Peru on the Pacific Ocean: two mini submarines were unloaded onto rail cars and transported up the Andes mountains to over 14,666 feet at Crucero Alto, then continued down the mountain by rail to Lake Titicaca at 3,812 metres (12,507 ft).
The team visited ruins in Peru before continuing south to Copacabana, Bolivia, where a parade was held in honor of the event.
[45][46] The effects of altitude on decompression and corrections to the tables or decompression computer settings to compensate for altitude would generally be included in entry level commercial and scientific diver training, and may be included in recreational diver training at some level, or may be split out as an additional training program for those who intend to dive at altitude, by which method the diver is not required to deal with the small addition to decompression theory if they don't need it, but have to pay for an additional course if they do.
