later, after hours in the water, as they rage, bicker, tell each other they love each other, night begins to fall and creatures appear around and underneath them .... this of course ticks all the boxes regarding our fears of the deep and the unknown, and the idea of becoming shark food. It shows that our position at the top of the food chain is provisional. But what is most scary is the detached indifference with which our lives are regarded by the rest of the universe, as we see the two tiny people bobbing up and down in the sea and frantically trying to attract passing ships.
Then, in that act of pure nihilism, she removes her body vest and goes under the water, as though offering herself up the ocean. Presumably she drowns herself before the sharks move on to her .... too late we see that they are missed and boats and planes start looking for them .... and the end credits reveal a dead shark being cut open and their camera discovered inside it.