"I'm Jim Cameron, and here's the deal: I love this stuff!" Well, duh. Starting to wonder if you'll ever go back to making plain old blockbuster movies again, Jim. Cameron looks like a kid in a candy store in this 3-D IMAX documentary, co-directed by Steven Quale, in which he goes on a series of mini-sub trips into the darkest depths of the ocean, observing geothermal vents and pigment-free sea critters. Along for the ride, in addition to the usual marine biologists, are a team of astrobiologists, who posit that if life on Earth can develop where the sun never shines, maybe it can similarly thrive in the oceans of worlds far distant from the sun. Cue the computer-generated images and some lavishly imagined trips to the moons of Jupiter. Fans of Arthur C. Clarke may be pleased, but fans of serious biology may bust out laughing at the goofily rendered aliens who show up. Best of all is hearing the scientists say things like "This is da bomb!" If it were a sci-fi movie, you'd never believe it.