The white dunes with blue lagoons — 155,000 hectares of pure silica sand and freshwater pools that appear only after the rains, on the edge of the Amazon estuary
The Lencois Maranhenses National Park (Parque Nacional dos Lencois Maranhenses) is a 155,000-hectare desert of white silica sand dunes on the coast of Maranhao state in northeastern Brazil — but it is not a typical desert. The park receives significant annual rainfall (1,600mm/year, concentrated in January-June), which accumulates in the interdune depressions between the 40-60m dune ridges as freshwater lagoons of extraordinary turquoise and blue colour (the colour produced by the high silica purity of the white sand beneath the transparent water). From June to September, the lagoons are at t…
The Lencois Maranhenses landscape is geologically young — the dunes are formed from river-transported silica sand deposited by the Amazon river system (the Amazon's sediment plume extends along the entire Maranhao coast, and the northeast trade winds sort and accumulate the finest silica particles into the dune fields). The park was established in 1981 as a federal protected area. The local communities (the quilombola communities of Afro-Brazilian descendants and the ribeirinho river-fishing communities of the Rio Preguicas) were allowed to remain within the park boundaries — an unusual provi…