Cirque de Mafate is the only inhabited corner of Réunion that no road reaches. Fewer than a thousand people live inside this amphitheatre, and everything they own came in on someone's back or slung beneath a helicopter. Sheer walls called remparts close the cirque on every side, and its only breach is the Rivière des Galets. Stand on the rim at Maïdo at first light and the floor lies under a white lid of cloud, ridges and roofs breaking through it, until the cloud climbs the wall and closes the view for the day. Ten hamlets, the îlets, are scattered across green shelves inside: La Nouvelle, Marla, Roche Plate, Grand Place, Aurère. Life in them runs on solar panels and batteries, groceries and cement arrive by helicopter rotation, and a nurse walks a round between them.
You go in on foot, or you fly. The gentlest way down is from Col des Bœufs, through the Plaine des Tamarins, a forest of tamarin trees hung with pale lichen, and on to La Nouvelle. Longer trails link the rest, and the walking is the whole experience: hours of switchbacks between hamlets, with the remparts standing over you the entire time. The basin was gouged out of Piton des Neiges, the dormant 3,070-metre volcano that built this half of the island. It is still often called a caldera, but geologists read it differently now. Vast landslides tore away the volcano's flank, and Réunion's extraordinary rain then spent millennia washing the rubble out to sea. That isolation made it a refuge: in the 18th and 19th centuries escaped slaves, the marrons, climbed in because slave-hunters would not follow, and the poor settlers who came after them stayed.