Sanctum (2011)

The only way out is down.

Master diver Frank McGuire has explored the South Pacific's Esa-ala Caves for months. But when his exit is cut off in a flash flood, Frank's team—including 17-year-old son Josh and financier Carl Hurley are forced to radically alter plans. With dwindling supplies, the crew must navigate an underwater labyrinth to make it out.