The Great Barrier Reef of Australia

Australia's luscious islands, cays and coral reef system of the Great Barrier Reef are awesome in scope and visuals -- in fact, this reef covers more of the world than any other entry on our list (approximately 135,000 square miles; the only living thing visible from outer space). All who encounter even a small portion of this gorgeous giant are dazzled by its aquamarine waters and honeycomb beaches. Even more beauty awaits you below the water surface: a maze of more than 2,900 spectacular coral reefs and countless marine life. Come to this area just off the coast of Queensland between June and October, so you can avoid the worst of Australia's oppressive heat.