Leviathan

Director: George P. Cosmatos

IMDB: http://www.imdb.com/title/tt0097737/

Review: Good enough action horror with a dodgy ending but it's hard to shake the feeling that it's just Alien underwater.

Rent it if: You want an enjoyable 90 minutes of claustrophobic monster horror.

And if you liked: Alien, The Thing, Event Horizon