This alternately breathtaking and rather pedestrian IMAX undersea exploration takes us to several reefs in the South Pacific. The film’s premise, as well as some of the adventures here, feel hand-canned rather than organic as the film strives to simultaneously entertain and warn of the eminent destruction of our saltwater domains. A diver in Fuji notices the local reef is dying, so he enlists the aid of a married research couple to investigate. They in turn interview scientists and naturalists, and document the beautiful and fragile ecosystems of such exotic locations as Australia’s Great Barrier Reef, the Rangiroa Atoll, and the coasts of Tahiti and Moorea. Directed by MacGillivray Freeman (Everest) and featuring the music of Crosby, Stills and Nash with narration by Liam Neeson.