Off the coast of Belize, at the centre of Lighthouse Reef atoll, the Great Blue Hole is a circular submarine sinkhole approximately 300 metres in diameter and 125 metres deep. Listed as a UNESCO World Heritage site under the Belize Barrier Reef Reserve System, it draws divers from around the globe to explore its submerged stalactites and deep-water sharks. The surface gleams in intense cobalt blue, a striking contrast against the turquoise lagoon surrounding it.

Quick Facts

• Access: Only by boat from Belize City, Caye Caulker or Ambergris Caye — journey takes several hours depending on departure point.
• Required level: Scuba diving reserved for certified divers (advanced level recommended; maximum depth ~40 m for stalactite zones).
• Snorkelling: Possible at the surface, though the site's main features are best experienced underwater.
• Recommended duration: A full day (early morning departure, late afternoon return).
• Season: Accessible year-round; calmest waters April to June.

What You'll See

The sinkhole's inner walls reveal stalactites and stalagmites formed over 10,000 years ago, when the cavern was above sea level. At depths of 30 to 40 metres, visibility is exceptional and light filters down in ethereal columns. Caribbean reef sharks, nurse sharks and occasionally bull sharks inhabit the deeper waters. Above the surface, the chromatic contrast between the hole's dark blue and the surrounding turquoise lagoon is breathtaking—particularly striking when viewed from the air.

History and Context

The site gained global recognition in 1971 when Jacques-Yves Cousteau led an expedition aboard the Calypso and declared it one of the world's finest dive destinations. Geologically, it is a drowned karst formation—an ancient limestone cave that collapsed as sea levels rose at the end of the last ice age. UNESCO inscribed the entire Belize Barrier Reef system, including Lighthouse Reef, as a World Heritage site in 1996.

Highlights of Your Visit

Diving into the Sinkhole

The descent along the vertical wall exposes massive stalactites, some exceeding six metres in length. The absence of currents within the sinkhole creates a technically accessible dive for advanced divers. While marine life is less abundant here than on exposed reefs, the geological spectacle more than compensates.

Encountering Sharks

Caribbean reef sharks are regularly spotted in mid-water. Many dive excursions include a stop on the outer reef of Lighthouse Reef, which teems with tropical fish and coral formations.

The Aerial Perspective

Flights in light aircraft or helicopters departing from Belize City reveal the sinkhole's perfectly circular form and striking colour gradations. This vantage point delivers the site's most iconic photography.

Photography Tips

Underwater, a waterproof camera with a wide-angle lens best captures the stalactites and the wall's depth. At the surface, morning light creates a glancing angle that accentuates the cobalt-to-turquoise contrast. From a plane or drone (check local regulations), the circular geometry is most dramatic. Avoid direct flash on corals.

Location and Access

The Great Blue Hole lies roughly 70 kilometres east of Belize City within Lighthouse Reef atoll. Access is exclusively by sea or air. Most dive operators based in Ambergris Caye or Caye Caulker offer full-day excursions. Light aircraft flights from Belize City allow for an overflight before or after diving. The site is not accessible to people with reduced mobility due to the maritime nature of access.

Nearby Attractions

• Half Moon Caye — nature reserve at the southern tip of Lighthouse Reef, home to magnificent frigatebirds and red-footed boobies.
• Ambergris Caye — Belize's premier island destination and frequent departure point for blue hole excursions.
• Caye Caulker — a more laid-back island, also serving as a base for dive operations.
• Belize Barrier Reef — the world's second-largest coral reef system, UNESCO-listed, framing the entire coastline.