Great Blue Hole Belize is caused by repeated collapses of a limestone cave system formed during the course of the last ice age.
The outer edge of the blue hole is barely a few feet underwater at high tide. The depth reaches 480 feet as the atoll lies on a geographic fault block, which has subsided into the basin through geologic time. It is quite difficult to get there.
This wonderful natural phenomenon is home to a premier diving site. It was made famous by Jacques-Yves Cousteau, who declared it to be the among the top scuba diving sites on the planet. He brought his ship called Calypso and one-man submarines in 1971 to explore the hole. The depths were charted out and the stalactites hanging from walls were examined.
In a sharp contrast to rumors, Cousteau's son, Philippe, did not die here. He was killed in a helicopter accident. It is also unlikely that Cousteau used an explosive to destroy the patch reefs. However, he did remove a tiny area, which helped the Calypso reach the Blue Hole.