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.
The film exhibits a respect for the craft and an empathy for human tribulations that have historically been ignored.
Like many things, like animals and people, they always evolve. When the first humans walked the Earth, they originated from Africa and were all black.