The Lençóis Maranhenses National Park is located in the Maranhão state – northeastern Brazil. It’s known for its vast desert landscape of white sand dunes and seasonal rainwater lagoons. During the rainy season, the valleys among the dunes fill with freshwater lagoons, prevented from draining due to the impermeable rock beneath. The park is home to a range of species, including four listed as endangered, and has become a popular destination for ecotourists.