Sink the enemy subs before they sink you. Just dial in their depth (which happens to be the answer to their multiplication problem) and let the depth charges fly. Avoid their torpedoes to keep your health above zero.

Keyboard Mouse Click on-screen number pad or use numbers on keyboard to enter depth AD keys or arrow keys to move Click on-screen X button or hit X key on keyboard to clear depth entry Hit spacebar to launch depth charge or click the Launch button