Players take on the role of a scuba driver, and it is up to them to navigate a series of underwater caves in search of their kidnapped friends. While exploring these caves, their air supply depletes so they must go up to the surface to refuel on air. Finding an air tank enables players to swim underwater for a longer period of time. If players have no air left, the game is over.

Useful items can be found scattered around the sea floor. These items include keys, which are used to unlock passages, bubble power, which allows players to trap creatures in bubbles which burst, extra speed, and monster suit, which scares off the creatures. Some passages are blocked by walls, and players must use their bubble power to destroy the wall.

Between caves, players have to destroy a shark which makes its way across the screen. If players make contact with the shark, their air supply diminishes. When the shark is destroyed, players proceed to the next cave. Later ones have less open surface, trickier passages, and faster creatures.