Lençóis Maranhenses National Park is a national park in Maranhão state in northeastern Brazil, just east of the Baía de São José. Protected on June 2, 1981, the 155,000-ha park includes 70 km of coastline and an interior composed of rolling sand dunes.
Composed of large, white, sweeping dunes, at first glance Lençóis Maranhenses looks like an archetypal desert, but in fact, it is not an actual one. Lying just outside the Amazon Basin, the region is subject to a regular rain season at the beginning of the year. The rains cause a peculiar phenomenon: fresh water is collected in the valleys between sand dunes and is prevented from percolating down by a layer of impermeable rock that lies underneath the sand. The resulting blue, green and black “lagoons” are surrounded by desert-like sand, and reach their fullest between July and September.
Brazil’s Lençóis Maranhenses National Park may not seem real to the uninitiated, but this phenomenal park, a direct shot 1,662 miles north of Rio de Janeiro in Maranhão state, is neither a mirage nor a movie set. It is at once one of the world’s most dramatic sandscapes — otherworldly dunes broke up by cerulean lagoons that pepper the sandy hills between March and September — and one of the world’s least beaten paths.
The vegetation of the Park has the influence of three diverse and rich biomes, the Cerrado (savanna), the semi-arid Caatinga, and the Amazon. In its 155 thousand hectares, it is home to diverse and fragile ecosystems, such as restinga (vegetation with marine influence), mangrove,s and dunes, the last ones being the main attraction of the National Park due to the lagoons formed during the rainy season.
Much of the territory of the Park is dominated by a landscape that cannot be found anywhere else on the planet: a succession of white sand dunes whose curves, when viewed from above, resemble large sheets stretched out in the wind. The park was featured in the Brazilian film The House of Sand. Kadhal Anukkal, a song from an Indian Tamil language film Enthiran starring Rajnikanth and Aishwarya Rai Bachchan was also shot here. The films Avengers: Infinity War (2018) and Avengers: Endgame (2019) used the park’s landscape as the planet of Vormir.
According to Wikipedia/ unesco