Pohnpei

Everything runs from Kolonia by day boat, and the crossing is part of the day: the lagoon is wide, so crews motor across flat inside water before they reach the barrier reef, and the passes are worked to the tide rather than to a fixed departure time. Two dives is the standard morning, with the surface interval spent in the lee of the reef top. Ant Atoll, off to the southwest, is run as its own full day rather than squeezed in between pass dives.

The island is volcanic and ringed by barrier reef, and the diving splits along that line. Inside, the lagoon shelves gently over patch reef and stays diveable when the outer edge is wind-blown, so it earns its place as a second tank rather than as the reason to come. Outside, the reef face falls into open water, and the cuts through it concentrate fish into a narrow strip of moving water where divers tuck in against a corner and let the animals come to them.

It suits divers who can accept a small scene. Operator choice is limited, boats need numbers to run, and plans shift with the wind on the reef top, so a week here works better with slack days built into it than with a fixed schedule. Divers who want shark and jack action without a queue of boats on the mooring will usually find it; anyone who needs a choice of resorts and a full night-dive programme is better served elsewhere in Micronesia. Nan Madol's basalt ruins fill a surface day.