The terror doesn't come from gruesome shark attacks. So if that's what you're looking for, you'll be disappointed. This movie strikes a deeper chord than typical blood-and-gore, shock-fest horror movies; and it may be that desensitized viewers who are incapable of genuine human emotion and empathy will not appreciate it. This film is about real psychological, existential terror -- similar to the effect achieved by Werner Herzog's Grizzly Man.