Maui, Molokini & Lānaʻi

Almost everything here runs on the trade winds. Boats leave Māʻalaea Harbor early because the channel builds a chop by late morning, so a two-tank crater trip is usually finished before lunch and the site is handed over to the snorkel fleet. Molokini is a state Marine Life Conservation District, so boats pick up day-use moorings instead of anchoring and the reef is closed to fishing. The running order is decided on the ramp — the outer rim first if the ocean is flat, the sheltered inside if it is not — and afternoons go to shore entries along the south and west coasts.

The islands are young volcanic rock and the terrain follows from that. Molokini is a drowned tuff cone, and the standing arc of rim takes the trade swell off one flank, leaving a floor of sand and coral heads that shelves out gradually toward the tips of the crescent. The seaward face is the opposite: open ocean, nothing to hold on to, and a current running along the wall. Lānaʻi is different again — solidified lava left tubes, arches and roofed chambers, so those dives are about architecture and light rather than depth.

What sets the diving apart is what lives on that rock. Hawaiʻi sits a long way from any other reef system, and roughly a quarter of its shore fish species are found nowhere else, so an ordinary dive turns up fish a well-travelled diver will not recognise. The trade-off is a coral fauna that is thin by Indo-Pacific standards. Humpbacks arrive for the winter, but they are not really a dive: federal rules hold vessels and swimmers 100 yards off, so the season is heard more than seen, and the same winter swell can shut the outer rim and the Lānaʻi crossing for a day or two at a time.

It suits divers travelling with people who do not dive. Trips are half-days, the boats are comfortable, and nobody has to build a holiday around the diving: a week can be two or three boat mornings plus a handful of shore dives at your own pace. Watch the altitude if you are driving the Haleakalā summit road, which climbs above 3,000 m and needs to wait until well after the last dive. Anyone wanting dense soft coral, big schooling pelagics or a liveaboard rhythm should look further west.