The deluged dunes

White sand meeting azure water is a common sight in Brazil, and it's not limited to the nation's more than 2,000 beaches. The nooks, crannies, crypts and channels amid the dunes of Lençóis Maranhenses National Park are filled each year by rainwater and retained by solid rock deep below the sandy surface that prevents drainage. From the air, this nearly 15,500-square-kilometre desert landscape looks like a patterned blanket of dunes and lagoons… until the water evaporates in the dry season.