Howard Hall’s sub-aquatic 3D trip opens with one of the most effective IMAX sequences yet: a static shot of a calm lagoon so lifelike you might feel the urge to dip your toes. Then the camera dives beneath the surface and we’re presented with a kaleidoscope of sea creatures the likes of which few of us have seen. The effect is like immersing one’s head in a giant aquarium.The close-ups, too, are often breathtaking. When Jim Carrey’s sufficient voiceover describes the propulsion system of the bizarre leafy sea dragon, the camera closes in to reveal a row of microscopic fins seemingly invisible to the naked eye. It’s that kind of detail that makes a the film such an immersive experience. An educational one, too.