Your task as a fleet commander is to escort a convoy from one end of the map to the other within a set time limit, with at least half the convoy vessels surviving the U-boat wolfpack hiding in the depths. The fleet commander has six destroyers for protecting the convoy and clearing the sea of submarines. The ships are equipped with sonar to discover the submarines and a number of depth charges and torpedoes to destroy them with. Only a limited amount of moves may be made during each turn.
A second player may join the game, playing as the submarine commander. Submarines may lay at the sea bottom (invisible to sonar), periscope level (for firing torpedoes), or in plain sight above the surface. At the surface level, the surface ships may ram the submarines, thereby saving precious munitions.