Being trapped in a rusty scuba-diver cage with your sister on the bottom of the sea floor on a trip to Mexico doesn't leave room for many possibilities for dramatic action. Once reserved Lisa (Mandy Moore) and fun-loving Kate (Claire Holt) are able to break open the lid, they can make the occasional foray out into shark infested waters to grab a flashlight or spare air tank that have dropped from the boat above. Why not just swim straight up?
As Captain Taylor (Matthew Modine) keeps reminding them over the radio, they'll get the bends. It's a terrible thing to suffer, although only slightly worse than a script that repeats this fact about a dozen times. Thankfully for director Johannes Roberts, who has a few B-movies under his belt (The Other Side of the Door, Storage 24), the image of a shark popping out of the darkness with teeth bared will always be terrifying.
There are some tense moments, and Moore and Holt's performances are about as good as could be hoped for considering they are behind scuba masks most of the time. But even at 89 minutes, you can feel the oxygen running out of this movie.