If you're into WWII submarine movies, and have 3? hours to spare, you oughta watch Das Boot. I watched the director's cut on DVD last night, and god damn it was long, but it was worth it. I had heard that it's one of the best submarine (well, in this case, u-boat) movies ever made, and while I haven't seen them all, this is definitely the best I've seen. Although, on the more humorous side, Operation Petticoat has to be my second-favorite. :)