A unique variant (precursor?) of Battleship. The game is a three dimensional board. Players hide their submarines and a mine on the three underwater levels, and place their surface ships on the top level. Players move a ship to a desired grid location and then fire a depth charge, marking off hits, near misses, and misses. Opposing submarines can fire a torpedo at surface vessels that are in the same column. Play alternates back and forth until one player sinks all three of his opponent's subs or all of his opponent's surface ships (almost never happens). - BoardGameGeek