The largest and longest coral reef in the world is also the most well-known: the Great Barrier Reef.
It stretches over 1,250 miles (2,000 kilometres) off the north-east coast of Australia in the Pacific Ocean and its width ranges between 37-155 miles (60-250 kilometres).
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In total, the reef system covers approximately 132,900 square miles (344,400 square kilometres), which makes it roughly the same size as Japan. In fact, it’s so large that it can be seen from space – both in satellite imagery and in photographs that astronauts have taken from the International Space Station.
The Great Barrier Reef actually consists of around 2,500 reefs, which have been formed by the skeletons of coral polyps and hydrocorals. The reef is estimated to be 500,000 years old, but it began taking shape as we know it today around 8,000 years ago.
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Temperatures in the Great Barrier Reef remain relatively stable throughout the year; between 21-38°C (70-100°F). However, the reef is threatened by rising temperatures, which causes mass bleaching of its corals.
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The Great Barrier Reef is home to over 1,600 species of fish, 133 shark and ray species, 30 species of whale and dolphin, 400 coral species, 4,000 species of mollusc and six out of the seven sea turtle species. Endangered species such as the large green sea turtle and the dugong can also be found at the reef.
It’s this biodiversity and scientific importance that led to it being classified as a UNESCO World Heritage Site in 1981. The American news company CNN named the Great Barrier Reef as one of the Seven Natural Wonders of the World in 1997, alongside the Aurora Borealis, Grand Canyon and Mount Everest.
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Top image: an astronaut aboard the International Space Station as part of the Expedition 45 crew used a powerful lens to photograph three reefs in Australia’s Great Barrier Reef on 12 October 2015. Credit: M. Justin Wilkinson, Texas State U., Jacobs Contract at NASA-JSC
