The Bazaruto Archipelago is five islands off southern Mozambique with no rock in them at all. They are made of sand that came down a river. The Save once emptied its load here, and the wind piled it into a dune barrier joined to the mainland. Then the river shifted course, the sea drowned the low ground behind the dunes, and the ridge became the islands there are now. The dunes are still going. On Bazaruto's eastern shore they reach about ninety metres, and the walk up the windward flank is slow, sinking work. From the crest there is ocean on one side and inland lakes on the other, and the way down is a few seconds of running through sand that pours away underfoot. The light aircraft hop from Vilanculos is the only way to read it whole — five sand islands ringed in jade and deep blue, with tide-drawn banks curling between them. From the ground you see a beach; from the air you see how the whole thing is built.
Two Mile Reef lies in the clear channel between Bazaruto and Benguerra, shallow enough that a snorkeller sees what a diver does, rays and turtles over the coral heads. Out over the seagrass, boats drift for dugongs. The last population in the western Indian Ocean grazes these shallows, a few hundred shy animals. A sighting is a grey back and a nostril breaking the surface for a second, and guides here are honest that many mornings pass without one. Humpbacks break their migration offshore from July to October, and all five of the region's sea turtles nest on these beaches, which nowhere else in this ocean can say. On tiny Santa Carolina, roofless walls and an empty chapel stand among the palms, a hotel walked away from at independence in 1975. As the tide drops, long white spits rise out of the shallows, nothing on them but bird tracks. They belong to the sea half of every day, so you walk one, and a few hours later the ribbon you stood on is gone.