A fun piece of throwaway cinema, "The Shallows" is a sleek, beautifully shot, and mostly satisfying thriller that plays it smart and simple, only faltering by opting for a schlocky climax. It's not the new Jaws by any stretch of the imagination, but where that movie transcended genre, "The Shallows" cleverly plays with it. Blake Lively ("Green Lantern," "Savages") carries its brisk 87 minutes almost entirely on her own, aided by a few co-stars, the most prevalent of whom is a seagull.