Australia's Great Barrier Reef

The Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organisms. This reef structure is composed of and built by billions of tiny organisms, known as coral polyps. It supports a wide diversity of life and was selected as a World Heritage Site in 1981.CNN labeled it one of the seven natural wonders of the world.The reef is located in the Coral Sea, off the coast of Queensland, Australia.

An underwater sculpture park filled with "bodies" feature among the most viewed Nat Geo News photo galleries of 2011.

Created by Mexico-based British sculptor Jason deCaires Taylor, the Caribbean installation is intended to eventually cover more than 4,520 square feet (420 square meters), which would make it "one of the largest and most ambitious underwater attractions in the world," according to a museum statement.
In doing so, Taylor hopes Mexico's natural reefs, which are already stressed by marine pollution, warming waters, and overfishing, can catch a break from the approximately 750,000 tourists who visit the area each year.