With the exception of a few specially designed models, most under-water cameras today employ no means of pressurizing, or at best merely have a Schrader valve fitted to the case which can then be pressurized, prior to each dive, with a few strokes of a bicycle pump. This method has one severe drawback in that the majority of camera cases are better able to withstand external rather than internal pressure. The chances of a case exploding or blowing a gasket while pressurized prior to a dive are far greater than those of implosion of a non-pressurized case in a comparable depth of water.