A clown fish laps up the good life on the Great Barrier Reef

Get here before global warming does. Coral bleaching caused by abnormally high sea temperatures has sucked the colour and life out of vast tracts of previously technicolour coral; reef scientists are predicting further devastation if temperatures continue to rise. 

The Great Barrier Reef is a UNESCO World Heritage area and is an extraordinary 345,000 square kilometres (bigger than Britain and Ireland combined). It is the only living thing visible from space. Sprawling off the coast of Queensland, the reef extends 2,300 kilometres from Lady Elliot Island near Bundaberg north to New Guinea and provides endless opportunities for finding Nemo, not to mention dugongs, turtles, reef sharks, blue-ringed octopus, dolphins, squid, sea snakes, sting rays, puffer fish, sea cucumbers, anemones and giant clams.

Around two million visitors come here every year to snorkels, scuba dive and gawk from glass-bottomed boats or low-flying airplanes at the psychedelic coral formations and fluorescent fish which together, make up the world's most varied marine habitat.

The lively city of Cairns and the laid-back town of Port Douglas further north are the most popular jumping off points for exploring the Great Barrier Reef. Numerous operators offer day trips from these centres. Other obvious bases include Airlie Beach, Townsville, Heron Island, Lady Musgrave Island, the Whitsunday Islands, Magnetic Island and the coral outcrop of Fitzroy Reef Lagoon. More than a thousand islands are scattered among the reef.

The water is warm enough for year-round diving, but April to November are the best times to visit; the water is coldest from June to August yet rarely drops below 22 degrees C.

Around November, lucky divers may be able to witness the surreal sight of coral spawning, as sperm and eggs drift and combine in a white-washed underwater tryst. This phenomenon takes place at night and occurs up to six days after the full moon.