page_title: Underwater diving
section_title: Depth range
hierarchical_section_title: Underwater diving / Diving environment / Depth range
caption_attribution_description: English: Trevor Jackson returning from a 178 metres (584&#160;ft) dive to the SS Kyogle in Queensland, Australia.
context_page_description: Underwater diving, as a human activity, is the practice of descending below the water's surface to interact with the environment.
  Immersion in water and exposure to high ambient pressure have physiological effects that limit the depths and duration possible in ambient pressure diving. Humans are not physiologically and anatomically well adapted to the environmental conditions of diving, and various equipment has been developed to extend the depth and duration of human dives, and allow different types of work to be done.
  In ambient pressure diving, the diver is directly exposed to the pressure of the surrounding water. The ambient pressure diver may dive on breath-hold, or use breathing apparatus for scuba diving or surface-supplied diving, and the saturation diving technique reduces the risk of decompression sickness after long-duration deep dives. Atmospheric diving suits may be used to isolate the diver from high ambient pressure. Crewed submersibles can extend depth range, and remotely controlled or robotic machines can reduce risk to humans.
context_section_description: The recreational diving depth limit set by the EN 14153-2 / ISO 24801-2 level 2 "Autonomous Diver" standard is 20 metres (66 ft). The recommended depth limit for more extensively trained recreational divers ranges from 30 metres (98 ft) for PADI divers, (this is the depth at which nitrogen narcosis symptoms generally begin to be noticeable in adults), 40 metres (130 ft) specified by Recreational Scuba Training Council, 50 metres (160 ft) for divers of the British Sub-Aqua Club and Sub-Aqua Association breathing air, and 60 metres (200 ft) for teams of 2 to 3 French Level 3 recreational divers, breathing air.
  For technical divers, the recommended maximum depths are greater on the understanding that they will use less narcotic gas mixtures. 100 metres (330 ft) is the maximum depth authorised for divers who have completed Trimix Diver certification with IANTD or Advanced Trimix Diver certification with TDI. 332 metres (1,089 ft) is the world record depth on scuba (2014). Commercial divers using saturation techniques and heliox breathing gases routinely exceed 100 metres (330 ft), but they are also limited by physiological constraints. Comex Hydra 8 experimental dives reached a record open water depth of 534 metres (1,752 ft) in 1988. Atmospheric pressure diving suits are mainly constrained by the technology of the articulation seals, and a US Navy diver has dived to 610 metres (2,000 ft) in one.
caption: A technical diver using a closed circuit rebreather with open circuit bailout cylinders returns from a 600-foot (180 m) dive.
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