On the UNESCO World Heritage list since 1981, the Great Barrier Reef (GBR) is an icon of the natural world. The area contains the world’s largest collection of coral reefs, with 400 types of coral, 1,500 species of fish and 4,000 types of mollusks. It also holds great scientific interest as the habitat of threatened species such as the dugong and the large green turtle. Virtual dive this reef and look carefully for three such turtles hiding amongst the corals.