You have to recover treasure from the seabed in the least possible time. As each item is retrieved it must be carried up to the salvage vessel, continually traversing the surface. Control of diver is keyboard or joystick.
Like all divers you have limited oxygen. When this falls to 20kg a helicopter drops a new bottle.
Other hazards include two white sharks which swim across the screen, and an octopus which disappears and reappears in different locations.
One peculiarity is the way the diver is equally able to "swim" in the sky as the water. This may not be used to advantage as you will be penalised by a dramatic reduction in oxygen and a time.
There are five skill levels. On each the ship moves faster and the predators become more aggressive.
Having struggled to win, you may, however, be disappointed. Your "best time" is not updated from 999, the maximum.
Note: Warwick says this bug does not appear in production on versions.