There have, over the years, been a lot of terrific undersea documentaries, but if you want to know what distinguishes this new one, it comes down to a single word: technology. In Disney's Oceans, a new generation of digital cameras have been used to capture the spindly, slithery, downright otherworldly creatures that roam the ocean floor, and those cameras don't just bring you right up close. They capture, as never before, the literal, tactile texture of all those elegant sci-fi beings the palpitating softness of a giant jellyfish, the mattress-like belly of a blue whale (the single largest animal in the history of the world), the crinkly body of a ray so svelte and multicolored it looks like a rippling Hermès scarf.
''Down here,'' intones the film's narrator, Pierce Brosnan, ''it's like nature has given anything a try,'' and the movie keeps astonishing you with the truth of that. Just when you're certain that you've gawked at the oddest life-form that 2 million years of evolution has ever coughed up, Oceans will dazzle you with something even stranger: a crustacean that resembles a giant surreally spiky insect, a stonefish that's literally like a rock that moves, or a good old cuttlefish, which has a lethal food-grabber that shoots out of its maw like something from Alien VII. That narration, spoken by Brosnan in the plummiest of storybook tones, takes you back to the old days of Disney anthropomorphism (''A hermit crab who has put on a little weight needs more spacious accommodations!''). That's enough to turn Oceans into a nostalgia trip for parents, even as it makes the ancient life-forms of the sea seem glisteningly new. A-