Great Blue Hole

The Great Blue Hole, Belize's most famous natural landmark, is a 125m deep limestone cave originally formed over water surface during ice age, when much of Earth’s water was in the form of glaciers and global sea level much lower. World-renowned scuba diving site, it was made famous by French explorer and naval officer Jacques Cousteau whose research on the sinkhole was first published in "Three Adventures: Galapagos, Titicaca, the Blue Holes" in 1973. Largest of its kind and under protection of Belize Barrier Reef Reserve System, the Great Blue Hole was declared a World Heritage Site by the UNESCO in 1996.