The player controls a submarine in hostile waters and must rescue the survivors of a mission which ended in disaster. Enemy submarines surround and will fire upon the player's ship if it enters sonar range. Each enemy submarine can fire up to five torpedoes; however, if it is destroyed before it uses all of their torpedoes, the remainder will be added to the player's arsenal. Other obstacles which must be avoided are mines, ice chunks and turbulent underwater whirlwinds. Once the survivors are located, it is necessary to dock with their pod, which the player has to approach with accuracy and care. A new mission will begin with a successful rescue.
