S1, E3: The Great Barrier Reef is vitally linked to the rest of the planet in many ways. Creatures travel for thousands of miles to visit in spectacular numbers, including tiger sharks, great whales, seabirds and the largest green turtle gathering on the planet. Alien creatures that are rarely seen, like nautilus, also rise out of the deep to visit the reef's warm waters. Weather systems travelling from across the Pacific also affect the whole reef, including mighty cyclones that bring destruction and chaos to the coral and the creatures that live on it. And it is weather patterns and climate change on a global scale that are likely to shape the future of the Great Barrier Reef and all its wildlife.