Coral has grown in this region for several million years but its modern form did not take shape until after the last ice age. As the polar ice caps started to melt some 10,000 years ago, sea levels rose and Australia's wide continental shelf was flooded. At the edge of that shelf corals grew and, keeping pace with the rising sea levels, they formed the Great Barrier Reef as we know it today.

Corals grow in an endless variety of plates and branches with a myriad of vivid colours and intricate shapes. One single lump of interconnected coral on the Great Barrier Reef weighed fifteen tonnes and was made up of 30 million individuals. Hard corals build a limestone skeleton beneath their living tissue so that as the colonies expand and grow whole reefs are formed.

For most of the year turtles glide through the azure water feeding on anything from marine grasses and algae to small coral creatures, such as jellyfish, molluscs and sponges. Whilst they can stay submerged for hours and they roam the seas for years on end, they need to haul ashore on the islands and beaches of the Great Barrier Reef to lay their eggs.