Belize Barrier Reef

One of the greatest marvels of the marine world, the 300-kilometre-long Belize Barrier Reef is located along the Central American country's Caribbean coast. It's part of the larger Mesoamerican Barrier Reef System that runs from Mexico's Yucatan Peninsula to Honduras and is the second-largest reef in the world behind the Great Barrier Reef in Australia. Declared a UNESCO World Heritage site in 1996, it's remained relatively healthy even as many of the planet's reefs are threatened by climate change.
© Tom Till/Alamy