While vacationing in Mexico, two sisters (Mandy Moore and Claire Holt) go shark diving in an iron cage. But the cable holding the enclosure snaps, and they plummet to the seabed at the depth of the title. Director and co-writer Johannes Roberts' claustrophobic, nerve-racking thriller, which is plausible enough to be more frightening than many horror movies, confronts the resourceful siblings not only with the predators they were meant to be observing in safety but with a rapidly dwindling supply of oxygen as well. As they struggle to survive, and the skipper (Matthew Modine) of the boat they were lowered from tries to organize a rescue, themes of forgiveness and self-sacrificing love are briefly showcased. Probably acceptable for older teens.

Watch out for: Some gory and gruesome images, a single rough and a couple of crude terms.

Rated: A-III, adults; MPAA: PG-13