Run Silent, Run Deep. Clark Gable and Burt Lancaster as the captain and XO of a submarine on patrol looking for Japanese shipping to sink. Utterly brilliant; the 90 mins goes by so quick.
Crimson Tide is quite obviously based on this. Burt Lancaster should take up command of the submarine but Clark Gable, whose own submarine was sunk in the same area a year before, gets the command and the two oppose each other.
8 or 9/10 I'd say.