Yay! This is one of those little seen horror movies I get excited about. It feels like only an exclusive group has seen it. For a fan of haunted house movies, well...even though there isn't a house, you should see this.
I've spoken before about the problem with ghost stories. Unless you let your ghosts physically interact with the world like a Poltergeist, there is only so much damage they can do. They can drive you insane, sure, but if you want a body count there is only so much a disembodied spirit can do. I think most of us are fine with suspending our disbelief of a ghost turning on a record player or slamming a door. When ghosts get all punchy, they lose their unique status in the monster world.
Below solves this problem by making the environment so fragile that the slightest noise or misstep can result in death. Set in an allied submarine during the height of World War 2, the crew is harboring a couple of very dark secrets. They stop at the wreckage of a sunken British hospital boat and save a small handful of survivors. One of these, a lady played by Olivia Williams (of Rushmore fame), begins encountering strange things on the sub which leads her to places she doesn't belong. To say much more gives away some guessable and not so guessable twists.
Darren Aronofsky wrote this and David Twohy directed. As I am famously in the bag for Aronofsky, I will admit to some bias here. Bruce Greenwood plays the troubled captain well. Zach Galifinakis (years before the Hangover) is great as Weird Wally, the only one on the ship who can understand the supernatural. Ron Livingston also turns in a great performance as an officer trying to help while keeping the secrets of the sub.
The whole thing drips with claustrophobia and tension. Submarine movies can be tense enough without worrying an enemy sub will hear your ghost playing a Benny Goodman record at full volume. I think this is a genre mashup that works exceedingly well. Check it out.