Great Blue Hole day trip

This is a dive day first and foremost. The hole is a drowned cave in the middle of Lighthouse Reef atoll, a circle about 318 metres across and 124 metres deep that formed when the sea stood much lower, and Jacques Cousteau charted it from the Calypso in 1971. The usual dive goes to around 40 metres for five to ten minutes, past ledges hung with old stalactites and often with a few reef sharks in view. Two shallower reef dives follow, and plenty of divers rate those above the hole itself.

Shops on Ambergris Caye need eight to ten divers to make the run, so trips go mostly midweek, and the boat ride from the cayes is at least an hour each way. Careful shops want advanced certification for the depth. The rim, about 5 metres deep before it slopes to a near-vertical wall, carries coral, groupers, angelfish and parrotfish.