The Lençóis Maranhenses National Park is located in Maranhão state, in northeastern Brazil. It is an area of low, flat, occasionally flooded land, overlaid with large, discrete sand dunes. It encompasses roughly 1000 square kilometers, and despite abundant rain, supports almost no vegetation.
The National Park is quite extensive and has no access roads. Because of the nature of the park's protected status, most vehicles are not permitted access. Entrance to the park is made exclusively by 4-wheel drive trucks.
Composed of large, white, sweeping dunes, at first glance Lençóis Maranhenses looks like an archetypal desert.
In fact it isn't actually a desert. Lying just outside the amazon basin, the region is subject to a regular rain season during the beginning of the year. The rains cause a peculiar phenomenon: freshwater collects in the valleys between sand dunes, spotting the desert with blue and green lagoons that reach their fullest between July and September.
The area is also surprisingly home to a variety of fish which, despite the almost complete disappearance of the lagoons during the dry season, have their eggs brought from the sea by birds.