Before attacking your opponent, freely build your submarine by selecting 10 "compartment" tiles that represent its equipment.

In the play area, your submarine is represented by a figure which indicates its position relative to its enemy (in Fore, Aft, Port, Starboard) and range (close-range or distant).

During the game you will use your 5 crew members to activate your submarine's compartments. Various effects can thus be triggered, and in particular effects that will deal crippling damage to your enemy submarine.

You win when your enemy’s control room has been destroyed, or when all his crew members have been eliminated.