Great Blue Hole

The Great Blue Hole is a large submarine sinkhole located within Lighthouse Reef Atoll off the coast of Belize, noted for its circular shape and deep blue interior. It is one of the most famous scuba diving sites in the world and part of the Belize Barrier Reef Reserve System.

The feature is approximately 300 metres in diameter and reaches a depth near 125 metres; its steep limestone walls drop from the rim into deep water. Divers visit for vertical walls, submerged limestone formations and the sense of diving a large, clear-sided sinkhole, while many visitors also view it from small aircraft for the full circular outline.

The Blue Hole formed as a karstic cave system during lower sea levels in the last ice ages and flooded as sea level rose at the end of the Pleistocene, leaving submerged cave structures and stalactites. Today it lies within the coral environment of Lighthouse Reef.

Geographically it sits about 70 kilometres off the Belize coast at Lighthouse Reef, surrounded by the wider Belize Barrier Reef and open Caribbean waters; access is by boat or aerial tour from Belize City and other coastal departure points.

• Size and depth: The sinkhole is roughly 300 metres across with a maximum recorded depth of about 125 metres, making it a notable deep marine hole in a coral atoll setting.
• UNESCO site: Part of the Belize Barrier Reef Reserve System UNESCO World Heritage Site, it is frequently visited by dive operators and aerial tour flights.

What to See #

• Lighthouse Reef Atoll: The Great Blue Hole sits at the centre of Lighthouse Reef Atoll, a coral atoll located southeast of the Belize mainland and part of the wider Belize Barrier Reef system.
• The Blue Hole: The vertical sinkhole itself is a near-circular marine cavity with steep walls and submerged limestone formations including stalactites that formed when the feature was dry.