The Great Barrier Reef is the largest living thing on the planet. And it is dying, which is all the more reason to visit it today. A slew of coral reefs and islands stretch some 1,400 miles (2,300 km) along the northeast coast of Australia off Queensland. One of the seven wonders of the natural world, the paradise can be explored in a variety of ways from snorkeling to seaplane tours. Cairns and island resorts make convenient bases.

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