The Maldives is twenty-six rings of coral laid along the equator in the Indian Ocean, and not one of them has anything in the middle. Each ring is a reef with a lagoon inside it and the islands strung around the rim like beads, 1,192 of them, none more than a metre or two above the sea. The word for that shape is Maldivian: atoll, from the Dhivehi atholhu, the one Maldivian word in everyday English. Living here means living on the water. From an overwater villa you go down wooden steps into the lagoon and are over living coral minutes after waking, usually alone in it. The bright shallows are the empty part. You swim out to where the pale sand floor ends and drops into blue. That edge is where everything holds: blacktip reef sharks working the shallows, green turtles grazing, parrotfish and snapper scattering off the wall as your shadow crosses it.
In Baa Atoll a small bay called Hanifaru fills with plankton faster than the tide can empty it, and from May to November reef mantas come in by the dozen to feed. When enough arrive they link into a slow rotating column of wings several metres across, turning just under your mask. It is the largest manta gathering known anywhere, and you meet it with a snorkel, not a tank. A boat or a seaplane puts you on a sandbank, an island of white sand ringed by bright shallows with not a building on the horizon. Some nights the water does something else again: plankton carried in by the waves sparks blue at every footstep along the waterline. It wants a moonless night, and plenty of walks end with only stars. All of this rests on almost nothing. More than four-fifths of these islands lie under a metre above the sea. Beside the capital there is now an island that was not there before: Hulhumalé, pumped up off the lagoon floor and set two metres high, a metre above everything natural around it.