This mesmerizing series asks what if the aliens were under your feet rather than over your head? Dr. Robert Ballard is the greatest underwater explorer of his generation, but he believes the tough job of shining a light into the abyss has only just begun. The oceans cover 71% of the planet – a mere 5% of which has been explored. In that 5%, Ballard has found the Titanic, the Bismarck, the carrier Yorktown and entirely new forms of life. Visit breathtaking sites on a surreal journey where cameras catch never-before-seen rock formations, lava vents and unusual species that call the ocean floor home, as Ballard explores these underwater worlds where no man has gone before. Alien Deep is Dr. Robert Ballard's voyage of discovery, his often inspired, sometimes opinionated, vision of our ocean planet – past, present and future. Produced by National Geographic.