Some whales are traveling from the Arctic Ocean to Baja to breed. The bad news is a whaling ship in the area is attacking them. You must use your submarine to shoot the nets or harpoons and radioactive debris to save the whales.
After you start the game, the whales will move from left to right along the bottom of the screen. The ship will start throwing down nets or harpoons, depending on the settings, to kill the whales. You must aim at the nets, in any direction and shoot them. After several nets/harpoons have been sent, radioactive debris will flow from the right side on the screen. This is up too high to hurt the whales but it can hurt you. You must shoot it as well. If your sub gets hit five times, the game is over. In a two-player game, one player is the sub and the other is the whaling ship.