Two sisters on Mexican vacation are trapped in a shark observation cage at the bottom of the ocean, with oxygen running low and great whites circling nearby, they have less than an hour of air left to figure out how to get to the surface.
Four teens explore a ruined underwater city and quickly find themselves in a watery hell as their adventure turns to horror. As they swim deeper into the claustrophobic labyrinth of caves, they enter the territory of the deadliest shark species in the ocean.