[Techniques of underwater intervention: means, methods, research and outlook].

In France, diving activities are practised by a large number of people, included recreational or sport divers, commercial and military divers. Different diving technics are used, depending on depth and duration of underwater interventions: human intervention under pressure (diving), one atmosphere submarine, remotely operated vehicle (ROV). The diver used specific equipment and procedures with air, heliox (oxygen -helium), hydrox (oxygen-hydrogen) or hydreliox (oxygen-hydrogen-helium) breathing gas mixtures; and for decompression, specific tables adapted to gas mixtures and underwater time exposures. In 1988, six Comex and French Navy divers worked at a record depth of 534 msw with hydreliox and in 1992 a world record onshore dive at 701 msw was performed by Comex in Marseille. These dives showed the efficiency of hydrogen diving at very deep depth. Among a lot of submarines built for undersea works, the latest in the range of Comex's innovative submarines, the "Remora 2000" combines the functions and instrumentation of an oceanographic subsea vessel with eye catching design of a recreational submarine. Now, ROV's replace more and more the diver on oil subsea offshore fields.