The Bijagós Archipelago is eighty-eight islands of a drowned river delta off the coast of Guinea-Bissau, in West Africa, low islands of forest, mangrove and palm in a shallow sea that walks out twice a day, holding the largest green-turtle nursery in Africa, hippos that swim in salt water and a society run by its women, and it is crossed by wooden pirogue from island to island. The islands are a biosphere reserve, and the Bijagó people who live on them keep their own order, with the women choosing their husbands by carrying a plate of food to the man they want and the elders keeping the sacred islands closed; the narrow pirogue is the archipelago's only real transport, and the crossing is half the experience, mangrove walls sliding past, spray over the bow and a helmsman reading channels that shift with the tide, since twice a day the tide drops and the archipelago doubles in size, laying bare sandbanks and mudflats that were open sea an hour earlier. On Orango the hippos are among the few in the world that tolerate salt, swimming the channels between the islands and grazing the coastal grassland, walked to at the Anor lagoons.
The turtles are the archipelago's great event. Green turtles nest on Poilão and the beaches of the João Vieira park from June to December, peaking in August and September, when on the busiest nights over a thousand half-tonne females haul out onto a single two-kilometre beach, each spending an hour digging, laying and burying before turning back to the sea. Through the northern winter 600,000 to 900,000 waders feed on the tidal flats after flying down from the Arctic, godwits, knots and whimbrels probing the mud in flocks that stretch to the horizon, and in the villages the male weaver birds knot palm fronds into hundreds of ball-shaped nests that hang from a single tree like fruit. The Bijagós are islands where the sea walks out and the women decide, and the turtles have chosen them too.