He Revealed some of the ocean's deepest secrets-the Titanic, the Bismarck and new forms of life at hydrothermal vents. And the story of the man behind these discoveries is just as intriguing. New, in this one-hour companion to his upcoming 2021 tell-all menoir, National Geographic's Bob Ballard reveals the inside stories behind his most exciting discoveries while sharing the personal triumphs, challenges and tragedies that led him to them.