Which Brazilian national park is famous for its seasonal sand dunes and freshwater lagoons?

Which Brazilian national park is famous for its seasonal sand dunes and freshwater lagoons? Lençóis Maranhenses National Park is the answer. Located in Maranhão in northeastern Brazil, it is known for vast coastal dune fields interrupted by clear lagoons that appear during the rainy season.

The park was created on 2 June 1981 and covers roughly 155,000 hectares. Although its landscape resembles a desert, it receives substantial rainfall—around 1,200 millimetres annually. Much of that rain falls from January through May, filling the hollows between the dunes. An impermeable layer beneath the sand helps hold the freshwater in place.

The dunes are shaped by sediment carried toward the coast by rivers including the Parnaíba and Preguiças, then driven inland by strong winds. Some dunes rise to about 40 metres. The lagoons are temporary: as the dry season advances, evaporation causes many of them to shrink or disappear. The park also contains mangroves, restinga vegetation and wildlife adapted to this shifting wet-and-dry environment.