Watch Fearless Planet Season 1 Episode 5 Online

How can the biggest living thing on the planet survive almost anything? How did it get to be so big? And who really is the biggest killer on the reef? Working with geologists and marine biologists, extreme adventurer Will Gadd gets up close and personal with the largest living thing on the planet (the only one you can see from space) — the Great Barrier Reef. The story of what makes this place the perfect location for the largest reef in the world takes Gadd far inland in search of clues to Australia’s mysterious past. This is the hidden story of a world that has died and been resurrected many times and it takes Gadd on an incredible voyage above and beneath the waves of Australia’s eastern seaboard. It has long been known that the remains of a much older reef are buried beneath today's Great Barrier. But just how old is it? The mission: to get a piece. Scuba diving to depths of 190 feet, the team retrieved a rare piece of that ancient reef. This was a first — scientists can now date that forgotten ancestor to 12,000 years old.