Long Island, Bahamas

Long Island runs north-south for about 130 km and rarely more than 6 km wide, a limestone strip with rocky Atlantic headlands on its north-east side and calm, shallow Bight of Acklins water on the other. Diving is split between the two: leeside reefs and coral heads sit in 9 to 18 m of gentle water reachable within half an hour of either resort dock, while the exposed coast and Conception Island, 21 km offshore (13 miles), hold the wall and open-water sites. There is no dedicated dive shop scene beyond the two resorts — Stella Maris in the north and Cape Santa Maria further south — which run guests out in small groups.

Dean's Blue Hole is the reason most visitors have heard of the island at all. It needs no boat and no booking to see: a short walk off the main road puts you on a sandy Atlantic-side beach with the shaft a few metres offshore, open to anyone who wants to swim or snorkel over it. William Trubridge has run the invitational Vertical Blue freediving competition here since 2008, and the hole's bell-shaped profile — a narrow mouth opening into a chamber some 100 m across — is exactly what makes it work for that sport: a diver on the rope drops through open water rather than skimming a wall.

The rest of the diving is more conventional and considerably less visited. Grouper Valley and Flamingo Tongue Reef are shallow, beginner-friendly stops close to shore; the M.V. Comberbach, a steel freighter prepared and sunk decades ago, sits at around 30 m for divers who want a wreck; and the coral wall off Conception Island, an uninhabited national park, is the one trip worth the extra distance, with elkhorn coral, turtles and reef sharks along a wall whose top runs about 14 m. None of it is heavily dived, which is as much the appeal as the blue hole itself for anyone who has already done the Bahamas' busier shark and wreck circuits further north.