-You start the game with three submarines. 
-Guide your submarine with the mouse pointer. 
-Press the mouse button to fire a torpedo upward toward the surface. 
-Press the keyboard space bar to fire a torpedo to the right. 
-Maximum of one torpedo at a time in each direction.
-Destroy all ten merchant ships to move on to your next mission.              
-Do not to torpedo quick e ships. It's a violation of international law. 
-Caution exploding depth charges, hostile torpedo fire, and magnetic mines.
-Your sub has a limited supply of fuel and torpedoes, and must be resupplied  frequently. A supply sub will pass by occasionally near the ocean bottom and       release a trained dolphin carrying fuel and torpedoes. By making contact with the  dolphin's supply pack, you can resupply your vessel. Whatever you do, don't torpedo the dolphin!