How a beach becomes a dune
A dune beside the sea is not an exception to how dunes form; it is a reminder that deserts are defined by moving sand, not by distance from the coast. Waves and currents shift sand onto shore. Once the upper beach dries, wind can lift and push the loose grains inland, where they gather into ridges and mounds.
The process depends on a steady supply of sand and places for it to collect. Plants can slow the wind and trap grains, helping a mound grow; their roots may also hold parts of it in place. Where sand remains exposed, the wind can keep reshaping the surface.
A meeting of two moving landscapes
On the Bazaruto Archipelago, dunes and ocean are linked parts of one coastal system. The sea continually rearranges sand along the shore, while wind carries some of it above the tide line. The dunes are therefore not simply dry land set against the water: their material has traveled through the same beach environment that borders them.
That connection also helps explain the sharp visual contrast. A dune’s dry, sunlit sand meets water whose color changes with depth, the seabed, and the light. From the shore, the boundary can look almost like a desert ending abruptly in turquoise—but it is a coastline in motion, with waves and wind continually shifting the edge between them.
