Up to about 30 years' ago diving activity was centred primarily on the naval services, who provided a lead in the development of equipment, techniques and procedures. Apart from one or two spectacular salvage undertakings, the main commercial activity up until that time was fairly low-key work in docks and harbours. The concept of saturation diving emerged from subsea habitats of which Captain Cousteau was one of the pioneers. This led the way to commercial development in support of exploration and the production of offshore oil and gas, and I believe that my friend Henri Delauze was one of the first to mount the subsea habitat on deck and provide a sealed bell to convey divers from the habitat to the seabed without change of pressure. A remarkable feature of offshore oil and gas technology in the North Sea has been the willingness of all concerned to exchange information regarding R&D. This has had a major effect on the advance in technology over the last few years. As far as diving is concerned, it is to some extent 'Hobson's Choice'. Legal patents are difficult to achieve in this field, and the casual nature of diver employment to date has meant that ideas and techniques circulate almost as freely as the divers themselves. In addition, the advertis­ ing of the new technologies which one has to offer almost auto­ matically means disclosure of what otherwise might be secret.