Lanyu — Orchid Island

A diving day is short and led entirely by the sea. Boats are small, leave from the harbour on the west side, and reach most sites in minutes, usually fitting two dives into a morning before the wind builds. When it is already up, guides drive the coastal ring road and pick an entry off the lava rock on whichever side is in the lee. Nothing is booked far ahead: the plan is made the night before and revised again at the slipway.

Underwater the island is what it looks like above, which is old lava. Ridges of black rock run offshore and fall away in steps and vertical faces, with boulder fields and swim-throughs in the shallows and clean sand only inside the bays. Coral cover holds on the ridge tops where the flow keeps it washed, and thins as you drop toward the blue. Because the current wraps the island, one site can be a slow swim on one tide and a fast ride on the next.

The island belongs to the Tao, and visitors are expected to take local custom seriously: the wooden tatala boats are not to be touched or photographed without asking, and the shoreline has its own restrictions during the flying-fish season that runs from spring into early summer. Operators will say plainly what is off limits and when. Underwater the payoff is fish that hold their ground on the corners instead of drifting off. It is a poor fit for divers still working on buoyancy or travelling on a tight schedule, and when the sea is up there is no easy fallback, only a day spent on land.