Convinced that the life aquatic holds infinite aesthetic potential, this British doc has all the characteristics of an oceanographic IMAX—swooping helicopter shots, impossible close-ups, grandiloquent narration (by Pierce Brosnan)—except physical scale and brevity. The film threatens to be a slog from the start, when pirouetting dolphins neglect to sing “So Long & Thanks for All the Fish.” But it’s impossible for 20 camera crews to scour the sea without dredging up a few stunning images. Best of all is a coral reef nocturnally transformed into a creeping mass of tentacles—a horror movie specimen rivaled only by the creatures of the lowest depths, including kaleidoscopic jellyfish out of a Kubrick acid trip. One can marvel at the eagerness of ball-making sand crabs and the tenacity of swimming polar bears; the survival tug-of-war between sea lions and killer whales makes for a poignant interlude. Those looking for a refresher course on the workings of the food chain should be in heaven. All others may yearn for a sushi break.