Belize
The easternmost atoll of the Belize Barrier Reef, about 80 km southeast of Belize City, best known for the Great Blue Hole natural monument and Half Moon Caye.
Lighthouse Reef encloses a lagoon of about 120 square kilometres. Near its centre lies the Great Blue Hole, a marine sinkhole 318 metres across and 124 metres deep, made famous after Jacques Cousteau called it one of the top diving sites in the world. Both the Great Blue Hole and Half Moon Caye are designated Natural Monuments, part of the Belize Barrier Reef Reserve System UNESCO World Heritage Site.