The IMAX 3-D camera takes the plunge once again to roam among the denizens of the world’s oceans. These underwater 3-D films are visually impressive, but there’s not much here we haven’t seen before. It’s ostensibly about sharks, but in a familiar cliché of these IMAX marine documentaries, our “host” is a sea turtle who regales us with narration (written by David Chocron and spoken by Geoffrey Bateman) that gently but pointedly reproaches the audience for humanity’s depredations against the ocean’s inhabitants. Beyond the usual it’s-all-your-fault stuff, the narration is banal and singularly uninformative; odds are you won’t leave the theater knowing much more about sharks (or turtles, or other fish) than you knew going in. Directed by Jean-Jacques Mantello, with noisy music by Christophe Jacquelin.