Not a great movie, but a very very good movie, that does exactly what it needs to do with the minimum amount of resources. As a two-hander, both leads are fine actors; the set up is brief and concise, and the premise is astonishlngly terrifying, considering how simple it is. I found myself longing for any shot of dry land just to relieve the terror of the watery isolation; their arc exactly matched that of the human condition; lighthearted, followed by bravery, followed by fear, followed by despair, fololowed ultimately by stoic acceptance. Daniel has all the male strengths, and weaknesses, and Susan has all the female strengths and weaknesses, and their stories describe the human gender arc. The film is a microcosm of hope, fear, life, death and the savage world, and if you're afraid of deep water, you're in for the ride of your life.