The Great Barrier Reef is one of the richest and most complex natural ecosystems on earth – home to a stunning array of animals, from microscopic plankton to 100-ton whales. From the coral cays of the outer reef to the Islands of the Torres Strait, the reef’s human residents work to find that critical balance between our needs and those of an ever-diminishing natural world.

Part 1 of 3
On the most protected island in Australia, 20,000 green sea turtles return to the biggest reptilian breeding colony on Earth.