Great Blue Hole

IslandsBelize

A dark circle 300 metres across in Belize's turquoise reef, dropping 124 metres, with stalactites forty metres down from when it was a dry cave.

September·Quiet month

Sep–Oct

The wettest, stormiest weeks — hurricane season peaks now, and this is when trips are most often blown out. Some of the caye's lodging, kitchens and dive shops shut for a few weeks; the monument never closes, and the sea is at its warmest, close to 30°C.

Year-round The shaft is always there: 124 metres of dark water, stalactites leaning at 40 metres, reef and nurse sharks patrolling them. What changes is the sea above — the crossing, the clarity, the boats.

The Great Blue Hole is a dark circle 300 metres across in the turquoise water of Belize's barrier reef, about 70 kilometres off the coast, and it drops 124 metres straight down. It was a cave. During the Ice Ages, when the sea was far lower, this was a dry limestone cavern with stalactites growing from its roof; when the ice melted and the sea rose, the roof collapsed and the ocean filled it. The stalactites are still there. Divers drop down the sheer inner wall to about 40 metres, where ten-metre spikes of stone lean out of the gloom and Caribbean reef sharks pass along the blue, and the layers in that rock record the ages when this was open air. Below them the hole gets darker and emptier. At the bottom there is no oxygen and nothing lives; for all its fame, the deepest part of the Blue Hole is dead. The famous view is from above. A small plane out over Lighthouse Reef shows the ring exactly as it appears in every photograph, a navy circle set in pale turquoise with its edge marked by a thin line of coral, and from the air its scale finally makes sense. Most visitors come by boat, and the boat ride is long, two hours or more each way across open sea, which is why the hole is usually the centre of a full day with two more dives on the reefs nearby. The shaft itself is almost colourless; the colour is on the shallow flats around the rim, where snorkellers float over coral heads, angelfish and rays in water a few metres deep. April to June is the calm window, when the winter winds have dropped and the water over the shaft is at its clearest. The Blue Hole is one of the very few places where you can swim down through the roof of a cave that the sea drowned at the end of the last Ice Age.

Worth knowing

Good to know

The deep descent needs advanced certification and punishes nerves — if you're not a confident diver, an aerial flight or a snorkel over the rim is the honest way to meet it.
The hole itself is a short, deep highlight, not the whole day — the standard Lighthouse Reef trip dives it first, then the brighter coral walls of Half Moon and Long Caye.
Bring a light, not just a camera — the best of the wall lies in shade at depth, where there's little colour to shoot, so the atmosphere counts for more than the photographs.
The sharks are no cause for alarm — Caribbean reef and nurse sharks slide along the shaft and pay divers little attention; they're part of the draw, not a danger.

Things to do

1
Descend the drowned cave wall
Drop down the sheer inner wall to about 40 metres, where ten-metre stalactites lean out of the gloom and Caribbean reef sharks pass along the blue. The dive needs advanced certification and a steady head: there is almost no coral or colour at this depth, and what you go down for is the dark, cave-like feel of the shaft.
2
See the perfect circle from the air
Fly out over Lighthouse Reef in a small plane and watch the navy ring resolve out of the turquoise — the view that made the Blue Hole famous, and the easiest way to grasp its scale.
3
Snorkel the reef flats around the hole
The shaft itself is dark and almost colourless; the life is on the shallow flats around it. Float over the coral rim, where southern stingrays cross the seagrass and the wall drops away into blue beneath your fins. Then move out to the reefs off Half Moon and Long Caye, where sea fans, sponges and grunts fill water two or three metres deep. Green and hawksbill turtles graze these seagrass beds and are usually unbothered by a snorkeller drifting quietly overhead.

Watch

Nearby

152 km