Get up close (but not TOO close) to those fascinating leviathans of the deep with this quartet of episodes from the "Blue Realm" series. Visit the high-risk, high-adrenaline sport of "Shark Divers"; see divers willing to abandon the safety of cages in "Shark Business"; scientists act to preserve the endangered "Whale Sharks: Gentle Giants"; and mantas off the Mexican coast are observed in "Giants of San Benedicto." 3 1/4 hrs. total on two discs. Widescreen (Enhanced); Soundtrack: English DTS.