Landmarks: Australia

"Great" doesn't even begin to describe the immensity of this reef. The Great Barrier owns several "world's largest" titles, including: coral reef system, single structure made by living organisms, and natural phenomenon visible in space, to name a few. This is a SCUBA and snorkeling paradise, teeming with marine life of all shapes and sizes. The variety of animals — whales and porpoises, exotic fish and turtles, and colorful coral — is a huge tourist draw. About 2 million people visit the reef annually.

New life: The first reefs began sprouting on Earth about 5 million years ago; the Great Barrier Reef is only 500,000 years old.

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