In the deepest, darkest parts of the oceans are ecosystems with more diversity than a tropical rainforest. Taking us on a voyage into the ocean -- from the deepest trenches to the remains of Titanic -- marine biologist David Gallo explores the wonder and beauty of marine life.

“Today we’ve only explored about 3 percent of what’s out there in the ocean. Already we’ve found the world’s highest mountains, the world’s deepest valleys, underwater lakes, underwater waterfalls … . There’s still 97 percent, and either that 97 percent is empty or just full of surprises.”