The Great Barrier Reef as a whole covers an area larger than Great Britain, but amazingly only seven per cent of it is coral reef. The rest is a variety of interconnected habitats including the world's oldest jungle, hundreds of islands, mangrove swamps, mysterious deep-water gardens, vast sand flats and meadows of sea grass - all full of amazing wildlife. A giant deep-water lagoon connects all of these, and many of the creatures that live in it are almost impossibly weird - from giant hammerhead sharks to the bizarre 'pearl fish' that lives its life up a sea cucumber's bottom. Marine life here also exists in spectacular profusion, as on the 100-year-old shipwreck of the SS Yongala, considered to be the greatest wildlife wreck on earth. The connections between all these environments mean that not only do they depend on each other, but without them the coral reef itself would not survive.

Originally released by BBC Worldwide Learning, 2012. Streaming video file encoded with permission for digital streaming by Infobase on November 21, 2019.