Great Barrier Reef

Beneath the blue bright waves of the Coral Sea off Queensland's east coast lies a wonder of the world: the rainbow-colored undersea fairyland that is the Great Barrier Reef. The world's largest living structure, the reef stretches for 1400 miles, and is made up of millions upon millions of tiny coral polyps, which cluster together and grow hard spiny skeletons. The corals themselves are white; the riot of bright colors that suffuses the Great Barrier Reef comes from minute algae, which live symbiotically with the corals and provide them with nutrients – and also from the thousands of polychromatic plants and animals that live on and thrive off the reefs, from seaweeds and fluorescent tropical fish to whales, dolphins and seabirds. The Great Barrier Reef has fascinated people all over the world ever since Captain Cook ran his ship aground on its spiky structure in 1770. 250 years later, it attracts two million visitors every year, who gaze down from helicopters or through glass-bottomed boats at the fantastical palaces the coral has crafted for itself, and snorkel and scuba dive amongst the teeming life of the reef.

But if you want to experience the beauty of the Great Barrier Reef for yourself, you may have to move quickly. Rising sea temperatures are changing the relationship between the coral and its algae from bounty to destruction, and coral scientists report that more and more coral reefs are bleaching and dying. Five years hence, the chance to see the beautiful reef in its technicolor glory may have vanished – and while there's hope that new species of coral may adapt to thrive in warmer seas, all we can know for sure right now is that the Great Barrier Reef as we know it may not be long for this world. So experience its wonders now, on a dive off classic reef resorts like Cairns or the Whitsunday Islands. Contrary to what you might think, swimming near the coral doesn't damage it, as long as you don't touch it or slather on chemical-heavy sunscreen, and responsible tourism to the reef actually encourages its preservation. And do cherish those memories and underwater Go-Pro shots: you might be looking for the last time upon one of the most beautiful sights in the world.