They are the rainforests of the sea: vast, multi-layered underwater towers brimming with brightly coloured fish, turtles and many other species set in an azure sea.
Coral reefs are among the most diverse, complex and vital ecosystems on the planet. They occupy only about 0.2 per cent of the ocean floor, yet are home to a quarter of all marine life. Reefs, though, are far from just pretty tourist attractions. These giant structures act as barriers, breaking up powerful waves and protecting coastal towns and cities from storm surges and beach erosion.