You are the anti-submarine warfare officer of a destroyer on patrol somewhere in the South Pacific. The sea below your ship is rife with enemy submarines. Your job is to destroy as many enemy submarines as possible within your 90-second firing window using your ship's main ASW weapon: The depth charge. Your ship can launch up to 4 depth charges at a time. Since depth charges are timed to explode at a pre-determined depth, you must place the aiming line at the depth you wish the charge to explode while gauging the time it will take the charge to reach that depth to explode on an enemy submarine. The aiming line can be moved vertically using the controller. Depth charges are not contact weapons so they will only destroy an enemy submarine upon exploding at the pre-determined depth. You may fire a depth charge by pressing the button on your controller. Your destroyer has two speeds which may be changed using the alternate button on the controller. If you manage to manage to rack up 2500 points or more, your firing window will be extended by 30 seconds.