Lençóis Maranhenses National Park, Maranhão, Brazil

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.
Lagoons in the "desert"
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: fresh water collects in the valleys between sand dunes, spotting the desert with blue and green lagoons that reach their fullest between July and September.