Australia’s Great Barrier Reef, just off the coast of Queensland, is the world’s largest reef system and one of the richest marine ecosystems on the planet. It’s so expansive it stretches more than 1,429 miles (2,300km) and can be seen from space, comprising more than 900 islands and over 2,900 individual reefs. It’s home to more than 9,000 known species, including the so-called 'Great Eight' – clownfish, giant clams, manta rays, Maori wrasse, potato cod, sharks, turtles and whales.