Iolo Williams explores Australia's Great Barrier Reef, one of the world's richest marine environments, in a bid to understand if the reef and the myriad of life it supports will survive for future generations.

Iolo Williams looks at the devastating effects of coral bleaching and tropical cyclones, but also uncovers incredible signs of regeneration and an abundance of marine life which continue to thrive despite the threats, giving hope for its survival.

In the final episode charting the journey of Naturalist and Conservationist Iolo Williams across the Great Barrier Reef, Iolo examines the changing face of the reef over the past 15 thousand years, building a picture of how the reef was formed, meeting the creatures and communities who have lived alongside it in harmony, and asks what part we can all play in the reef's future.