Diving is by definition, a man's stay under water, providing the physiological breathing conditions (diving with a breathing apparatus), or without (breath-holdor free diving). It begins when the diver dives and stops breathing surface air and ceases when it is again re-inhaled after resurfacing. There are many classifications and purposes of diving. Although diving is a wonderful sport, it is also a perilous one. The injured diver is transferred to the nearest hyperbaric chamber as soon as possible. To ensure that the entire diver's treatment process is adequately dealt with, and to avoid any possible complications as well as major disasters associated with hyperbaric chambers which occurred in the past of hyperbaricoxygentherapy (HBOT), good teamwork of a highly educated multidisciplinary team, high-quality equipment and compliance with all security protocols are needed. Protocols for the treatment of decompression diseases are selected according to the diver's clinical condition and presentation, and considering the degree of gas loading, diving profile and otherf actors. While providing treatment inside the chamber, divers are cared by specially trained personnel who may be nurses/technicians or doctors. Since underwater and hyperbaric medicine, regardless of its long history, which is longer than most medical specialties, is relatively young as a stand alone medical specialty, education, protocol drafting, good co-operation with other branches of medicine, statistical patient tracking and scientific research are of paramount importance to observe and study all the advantages and disadvantages, and to ensure the maximum use of hyperbaric oxygen therapy in modern medicine.