An underwater acoustic positioning system is a system for the tracking and navigation of underwater vehicles or divers by means of acoustic distance and/or direction measurements, and subsequent position triangulation.
Underwater searches are procedures to find a known or suspected target object or objects in a specified search area under water.
A lifting bag is an item of diving equipment consisting of a robust and air-tight bag with straps, which is used to lift heavy objects underwater by means of the bag's buoyancy.
An inspection is, most generally, an organized examination or formal evaluation exercise.
Diving equipment is equipment used by underwater divers to make diving activities possible, easier, safer and/or more comfortable.