Girl Sports Underwater divingFrom Wikipedia, the free encyclopediaThis article is an introduction to underwater diving by humans. For other uses of the term diving, see dive (disambiguation) and diving.Museum of Diving in WarsawInformal Recreational diving flagUnderwater diving is the practice of going underwater, either with breathing apparatus (scuba diving and surface supplied diving) or by breath-holding (freediving). Atmospheric diving suits or the saturation diving technique can be used to combat decompression sickness.Diving activities are restricted to relatively shallow depths, as even armored atmospheric diving suits are unable to withstand the pressures of most of the deeper waters of the world. Diving is also restricted to conditions which are not excessively hazardous, though the level of hazard acceptable to the diver can vary considerably. Occasionally divers may dive in liquids other than water.The term deep sea diving refers to underwater diving, usually with surface supplied equipment, and often refers specifically to the use of standard diving dress with the traditional copper helmet. Hard hat diving is any form of diving with a helmet, including the standard copper helmet, other forms of free-flow helmet and lightweight demand helmets.Recreational diving is a popular activity (also called sports diving or subaquatics). Technical diving is a branch of recreational diving. Professional diving (commercial diving, diving for scientific research purposes or diving for financial gain) takes a range of diving activities to the underwater work site. Public safety diving is the underwater work done by law enforcement, fire rescue, and search & rescue/recovery dive teams, and may be done by professionals or volunteers. Military diving includes combat diving, clearance diving and ship's husbandry diving. Underwater sports is a group of competitive sports using either free-diving, snorkelling or scuba technique, or a combination of these techniques.Training, types of equipment used and breathing gases used depend on the type of diving.Contents [hide] 1 History1.1 Free-diving1.2 Diving bell1.3 Diving dress1.4 Surface-supplied diving dress1.5 Development of modern diving operations1.6 Self-contained air supply equipment1.6.1 Open-circuit scuba1.6.2 Closed-circuit scuba1.7 Scuba systems during World War II1.8 Atmospheric diving suits1.9 Physiological discoveries2 Methods of underwater diving2.1 Diving without breathing apparatus2.2 Scuba diving2.2.1 Open circuit2.2.2 Rebreathers2.3 Surface supplied diving2.3.1 Surface oriented diving2.3.2 Saturation diving3 Dive sites4 Reasons for diving5 Diver training6 Diving hazards7 Other forms of underwater diving7.1 Diving in submersibles7.2 Diving by other animals8 See also9 References10 Further reading11 External linksHistory[edit]Further information: Timeline of diving technologyFree-diving[edit]Main article: Free diving