I've owned most of the submarine games, but my favorite was the least impressive for graphics. Any remember Microprose's ancient game, The Hunt For Red October?
That game came out around 1987. It raised howls from the DOD who recognized some of their secret technology in the game. Of course, the game maker just made educated guesses and hit the mark too close for the Navy's comfort.
Of all the sub games out, this one could teach you the finer points of modern sub tactics like no other. Eventually, the Navy recommmended the game to its own submarine officers as a use-at-home training tool...
Better games eventually appeared, but none of them offered a better platform for tactics.
My regards,
Widewing