Belize Barrier Reef

Diving here is organised around distance from the reef crest. From San Pedro or Caye Caulker the inner barrier is minutes offshore, and shops run two-tank mornings with an afternoon or night dive added on. The atolls are a different commitment: a full-day trip with two hours or more of open water each way, a stay at an atoll lodge, or a liveaboard that simply sits out there for the week. Placencia and the southern cayes work the same way for the sites off that coast.

The topography changes with each of those steps. Inside the barrier the reef runs as spur-and-groove, coral fingers separated by sand channels at easy depths and cut here and there by narrow gaps where fish funnel through. Offshore, Belize has three true atolls — Turneffe, Lighthouse Reef and Glover's Reef — and their rims work the other way round: shallow flats that end at a lip, then a face dropping into blue. The Blue Hole belongs to neither category, being a flooded karst sinkhole rather than a reef.

Set expectations for the Blue Hole accordingly. It is a dark blue-grey descent along a wall to an overhang of limestone formations, hanging at an angle that suggests the block shifted long after they grew, with little coral, few fish and only a few minutes at around 40 metres before the long ascent starts. Divers who go for the geology come back satisfied; divers expecting the reef photographs that sell Belize often do not. Boats usually pair it with a Lighthouse Reef wall and a shallow reef the same day, which is where the colour is.

The area suits divers who want variety inside one trip and will trade boat time for it. Mixed groups do well: Hol Chan Marine Reserve and Shark Ray Alley off Ambergris Caye are shallow, guided and busy, while the atoll walls and cuts give experienced divers depth and moving water. Anyone chasing whale sharks should build the trip around the March–June full moons, go out of Placencia with a licensed guide, and treat a sighting as possible rather than promised.