The Belize Barrier Reef is the largest barrier reef system in the Northern Hemisphere. It extends roughly 200 miles, and is made up of a series of coral reefs, cays and islands, many of which are covered with mangroves. It was designated a Unesco World Heritage Site in 1996, and added to its endangered list in 2009.
One of the greatest coral reef ecosystems in the world, the Tubbataha Reef in the Philippines, continues to prosper. Undersea coral walls that plunge more than 300 feet deep are home to some 600 species of fish and 360 kinds of coral, about half of all known species. According to experts, the ocean wilderness of Tubbataha Reef is about the closest thing to a true natural state for any reef in the world.
The Pitcairn Islands are a group of four volcanic islands in the South Pacific, mostly known from the famed mutiny on the British ship Bounty. Pitcairn Island itself is where many of the mutineers settled and where some of their descendants live today. That small island, with a population of 57, is the only one of the group that is inhabited.