Famed ocean explorer Dr. Robert Ballard delves into the deepest secrets of the world's oceans in this five-part documentary series from National Geographic. Deploying vessels that can reach the most remote depths of the seas and utilizing cutting-edge photographic equipment, Ballard reveals previously hidden species and ecosystems to the viewer that had been unexamined for thousands of years. 3 3/4 hrs. total on two discs. Widescreen (Enhanced); Soundtrack: English Dolby Digital 5.1; behind-the-scenes footage.