What is the great reef?

- Located in the Coral Sea, off the coast of Queensland, Australia

- Largest coral reef system in the world, stretching for over 2,300 km (1,400 miles)

- UNESCO World Heritage Site since 1981

- Made up of over 2,900 individual reefs and 900 islands, formed by billions of tiny coral polyps

- Supports an incredibly high biodiversity, including over 1,500 species of fish, 400 species of corals, 4,000 species of mollusks, 133 species of sharks and rays, 30 species of whales and dolphins, and many more

- Important for tourism, contributing billions of dollars to the Australian economy each year

- Under threat from climate change, ocean acidification, pollution, overfishing, and coastal development