Seen from the air, the dunes look like white linens hung out to dry on a windy afternoon. In fact, the name of this place, Lençóis Maranhenses, means the "bedsheets of Maranhão," the state in Brazil on the tropical northeastern coast where the half-moon-shaped dunes are found. By any name it is a magical desert, with wave after wave of shimmering white sand. Shoals of silvery fish swim in brilliant blue and green pools left behind by the rains. Shepherds lead caravans of goats over towering dunes. And fishermen head out to sea, guided only by the stars and the ghosts of old shipwrecks.
"It feels like a parallel world," says Carolina Alvite, former director of the 600-square-mile national park created three decades ago to protect this unlikely ecosystem. It's as if the sea near the Bahamas suddenly appeared like a mirage in the middle of the Sahara.
Only in this desert the mirage is real.