1. "The Hunt For Red October" 2. A little named movie starring Ed Harris and David Duchovny titled "Phantom." Off topic I just saw a movie with my son that had Ed Harris in it on Netflix named "The Way Back" and I highly recommend it.
I think my favorite, other than the above mentioned HFRO, is the 1957 classic: "The Enemy Below", with Robert Mitchum and Curt Jürgens.
Best to worst imo: Crimson Tide The Hunt For Red October Das Boot U571 K19: The Widowmaker I need to catch up with the others.
The best comparison to real submarine life is Down Periscope. Next in line, is U-571. Then, you can move onto K-19: The Widowmaker. K-19 isn't scientifically accurate by any stretch of the imagination, but it is cool nonetheless. The Hunt for Red October is by far the worst submarine movie ever... That is followed very closely by Crimson Tide. They are both completely and utterly screwed up and in no way accurate. ~Will Courtier~
IIRC there's a fairly good paranormal sub movie called Below. http://www.imdb.com/title/tt0276816/?ref_=fn_al_tt_1 (Heh, there's that Darren Aronofsky dude again)