Blue Hole

The Great Blue Hole Was Above Ground During the Last Ice Age

The formation that Belize calls its most famous natural wonder began as a limestone cave system when sea levels were significantly lower. As ice melted and sea levels rose after the last glaciation, the cave roof collapsed and flooded. The result, visible from space as a near-perfect dark circle against the turquoise shallows of Lighthouse Reef Atoll, is approximately 300 metres across and 125 metres deep.

Jacques Cousteau declared it one of the top diving sites on the planet in 1971 and the visibility of the site from aircraft has made it one of the most photographed natural formations in the Caribbean. A 2018 expedition involving Fabien Cousteau (Jacques’s grandson) and Richard Branson used submersibles to map the floor in detail, finding thick layers of toxic hydrogen sulphide at depth, below which virtually no life exists. The scientific significance – sediment and stalactite data that has helped reconstruct the timeline of the last ice age – is as substantial as the visual drama.

Getting There and Diving

The Great Blue Hole is accessible only by boat, roughly 43 miles east of Belize City in the barrier reef system. Day trips depart from San Pedro on Ambergris Caye (2 to 3 hours each way) or Caye Caulker (slightly shorter). Most tours leave around 5:30 to 6:00am to maximise time at the site. Book in advance, particularly December through April.

The hole itself is an advanced dive. Reaching the stalactite formations requires descending to 40 metres or more; Advanced Open Water certification at minimum is required by reputable operators. Visibility is often exceptional (sometimes over 30 metres) and marine life includes Caribbean reef sharks, bull sharks near the rim, nurse sharks, and large schools of midnight parrotfish. Snorkellers can enjoy the outer reef but not the interior.

Most day trips combine the Blue Hole with a stop at Half Moon Caye Natural Monument, home to several thousand red-footed boobies nesting in remarkable density. The reef surrounding Half Moon Caye is some of the best snorkelling in Belize.

Bases: San Pedro and Caye Caulker

San Pedro on Ambergris Caye is the main hub, with Victoria House Resort and Ramon’s Village Resort both offering integrated dive operations. Caye Caulker runs at a slower pace with smaller, more casual accommodation options. Both have seafood restaurants serving fresh Belizean and Tex-Mex food at reasonable prices.

Inland Belize

Cave tubing on the Caves Branch River, floating through Maya Mountains caves on inner tubes with headlamps, is one of the more memorable inland activities. Actun Tunichil Muknal (ATM Cave) is a more demanding archaeological tour into a cave system containing Maya skeletal remains and ceramic offerings – one of the more remarkable experiences in Central American archaeology.

Practical Notes

US dollars are universally accepted alongside Belize dollars (pegged 2:1 to the USD). Use reef-safe mineral sunscreens; Belize has restrictions on certain chemical formulations to protect the reef. Book Blue Hole tours at least a week ahead in high season.