During the late summer of 2001, Cameron, his pal Bill Paxton and a crack team of boffins took turns descending two and a half miles to the bottom of the Atlantic in two submersibles, each equipped with a 3-D IMAX camera rig and trailing specially designed Remotely Operated Vehicles to shine a light on the Titanic's rusting wreck, trawl its inner chambers and penetrate its secrets. The resulting documentary concoction is part record of the expedition itself and part testimonial to the ship and those who sailed in her. The film's strongest suit is its simple power of revelation, the immediacy and immersiveness of its encounter with the unknown. It may not have the organisation of 'art', but it's quite some postcard. (See also Expedition Bismarck.