"Below" by Yojimbo
An interesting undersea ghost story (or is it?) directed by the man responsible for cult sci-fi classic Pitch Black, this is similarly good-looking and atmospheric. The shocks are a little obvious, but it keep you guessing (is the sub really haunted, or are they just suffering paranoid ill effects from oxygen deprivation?) and Twohy creates a nice otherworldy feel, particularly in the diving scene on the exterior of the sub.