St Helena

Diving here is a small, personal operation. A couple of outfits work out of Jamestown, boats are small and groups smaller, and the run to most sites along the sheltered leeward coast takes minutes rather than hours. Days are built around the swell: the long rollers that periodically make the wharf landing awkward decide more than any timetable does. You will usually have a site to yourself, and dives get slotted around a morning of walking or of the island's history.

There is no coral framework to speak of. The island is basalt dropping straight into deep water, so sites are boulder slopes, undercut ledges, arches and short caverns, with encrusting sponge and algae in place of hard coral. Clarity swings with plankton and swell rather than with the calendar, and a thin wetsuit covers most of the year. Current is usually light, so the demanding part is rarely the dive itself — it is getting on and off a small boat in open ocean.

The fish are the surprise. Long isolation has left a shore-fish community with an unusually high share of species found nowhere else, and a guide can point out most of them in a dive or two; the species count is low, but numbers on the shallow ledges are not. The anchorage adds wreck diving shallow enough to repeat two or three times in a week, and the place rewards a slow, curious style rather than a hunt for the next big animal.

This suits divers who treat the destination as the trip rather than the diving as the trip. Getting here costs time and money, and the reward is emptiness: no second boat on the site, no queue at the wharf, and a small community that notices you came for the water. Anyone after warm tropical reef, coral colour or a reliable big-animal encounter outside the December-to-March window will find it thin.