Legendary Great Blue Hole of Belize

The Great Blue Hole — the world’s largest blue hole — is a massive underwater sinkhole off of the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll 60 miles (96 kilometers) east of the Belize mainland. The hole is near perfectly circular in shape, more than 1,000 feet (305 meters) across and 480 feet (146 meters) deep.

Lighthouse Reef Atoll Blue Hole

The Blue Hole is the result of repeated collapses of a limestone cave system formed during lower sea level stands in the course of the last ice age.

The outer edge is merely a few feet underwater at high tide. It’s 480 feet (146 meters) deep instead of the shallower 390 foot depth because the atoll is on a geological fault block that’s been subsiding into the basin through geologic time. It’s not an easy place to reach.

This incredible geographical phenomenon is one of the most astounding dive sites in the world, made famous by Jacques-Yves Cousteau who declared it one of the Top 4 scuba diving sites on Earth. In 1971, he brought his ship, the Calypso and his 1-man submarines to the hole to chart its depths and examine stalactites suspended from overhanging walls.

Contrary to rumors, Cousteau did not lose his son Philippe here — he died elsewhere in a helicopter accident. Neither did Cousteau randomly use explosives to destroy the patch reefs while navigating the Calypso in the Blue Hole. He did selectively remove — by limited blasting — a very small area to enable the Calypsoto reach the Blue Hole.

It has been likened by some to a journey into a prehistoric place in time. Great depth creates the deep blue indigo color that causes such structures to be known as ‘blue holes.’ Except for 2 narrow channels, coral surrounds the hole and breaks the surface in many areas at low tide.

Pederson’s cleaning shrimp are everywhere inhabiting the ringed and knobby anemones, and neon gobies advertise their cleaning services from the various coral heads. Angelfish, butterflyfish, hamnlets, and small groupers are also commonly seen. Elkhorn coral grows to the surface and purple seafans sweep at the calm surface waters, glittering their rich hues.