34. Great Barrier Reef, Queensland Coast

While the Columbus Reef illustrated in slide #33 looks like an almost uninterrupted wall of coral, the Great Barrier Reef off the east coast of Australia is made up of many detached, individual reef segments and atolls. At 2000 kilometers in length, the Great Barrier Reef forms the longest natural breakwater in the world. This photograph, taken off the coast of Queensland at Cairns, shows light cloud condensing over the reef. The Flora Passage through the reef is located slightly south and west of Cape Grafton, the peninsula headland toward the right of the frame.

The Great Barrier Reef, which is the largest structure on Earth built by living organisms, supports at least 350 different species of coral. The geological stability of the region has allowed the reef to continue to grow for more than 25 million years.

STS-51D, April 1985. Picture #23-34-054

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