Great Barrier Reef, Queensland, Australia

Great Barrier Reef, Queensland, Australia

This natural wonder includes more than 2,900 individual reefs and 900 islands stretching over an area of about 133,000 square miles – numbers that become even more amazing when you learn the reef was created by teeny, tiny marine invertebrates. Coral reefs are formed when colonies of coral polyps secrete hard exoskeletons made of calcium carbonate, slowly building an underwater home to support marine life of all shapes and sizes. That’s a feat worth protecting.