White sand dunes stretching as far as the eye can see, interspersed with turquoise-blue rainwater lagoons... The Lençóis Maranhenses National Park (a nature reserve since 1981), which stretches over 155,000ha, is unlike anywhere else in the world and must be seen to be believed. The site is at its most spectacular at the end of the rainy season, when the lakes overflow with water. Start at Atins for a hike or horse ride, or from the village of Barreirinhas to go down the Rio Preguiças by pirogue.