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Lençóis Maranhenses National Park
What is Lençóis Maranhenses National Park, and where is it?
Lençóis Maranhenses National Park is a 155,000-hectare protected area in Maranhão state, northeastern Brazil, along the Atlantic coast. Rolling sand dunes dominate the landscape, and during the rainy season from January to June, freshwater lagoons fill the valleys between dunes, creating a striking seasonal transformation.
Location and Coastal Setting
The park occupies 155,000 hectares in Maranhão state on Brazil's northeastern coast, just east of Baía de São José. Its 70 kilometers of Atlantic coastline form the eastern boundary, while inland borders follow the Parnaíba River, São José Basin, and the Itapecuru, Munim, and Periá rivers. The park sits in a region where multiple river systems converge with the ocean, creating a dynamic interface between freshwater and marine environments.
Sand carried by the Parnaíba and Preguiças rivers from the continent's interior reaches the coast, where Atlantic winds push it back inland up to 50 kilometers, building dunes that rise as high as 40 meters. This wind-driven sand transport continues to reshape the landscape, creating the barchanoid dune formations that characterize the park's interior. The dunes formed during the late Quaternary period and remain geologically young.
Seasonal Lagoons and Water Chemistry
The park receives approximately 1,200 millimeters of rain annually, concentrated between January and May, which contradicts its desert-like appearance. During the rainy season extending through June, water collects in the valleys between dunes, forming freshwater lagoons up to 100 meters long and 3 meters deep. These pools cover as much as 41 percent of the park's total area at their peak. An impermeable rock layer beneath the sand prevents drainage, allowing water to accumulate in what would otherwise be porous terrain.
Lagoon water maintains temperatures between 27.5 and 32 degrees Celsius with pH levels between 4.9 and 6.2, containing low levels of dissolved nutrients. When the dry season arrives, the lagoons evaporate rapidly, losing up to 1 meter of depth monthly. The lagoons often interconnect with each other and with surrounding rivers, creating a temporary network of freshwater pools that vanishes within months.
Endangered Species and Biodiversity
The park shelters four species listed as endangered on Brazil's official list: the scarlet ibis, neotropical otter, oncilla, and West Indian manatee. Beyond these four, the park contains 133 plant species, 112 bird species, and at least 42 reptile species. The lagoons support fish including the wolf fish, which burrows into wet mud layers and enters dormancy during the dry season when water disappears. The ecosystem extends beyond dunes to include restinga vegetation and mangrove areas.
Two oases or restingas exist within the park's interior: Queimada do Britos covering 1,100 hectares and Baixa Grande covering 850 hectares. These vegetated areas provide habitat distinct from the surrounding dunes and serve as refugia for species adapted to wetter conditions. The interconnected lagoon system creates seasonal corridors for fish and aquatic insects that depend on the temporary pools.
UNESCO Recognition and Protected Status
The park received official protection on June 2, 1981, establishing it as a national park under Brazilian law. In July 2024, UNESCO designated the site as a World Heritage Site, recognizing its exceptional beauty and unique natural characteristics. The designation acknowledged the park's singular position globally as a landscape where seasonal transformation creates an ecosystem found nowhere else in comparable form.
The park now attracts approximately 60,000 visitors annually, who engage in surfing, canoeing, and horse riding. The combination of protection status and growing ecotourism reflects international recognition of the site's ecological and aesthetic significance. The park's management balances conservation of endangered species with sustainable visitor access to this dynamic landscape.
Climate and Temperature Stability
The park experiences minimal seasonal temperature variation, with average annual temperatures between 26 and 28.5 degrees Celsius and annual variation of only about 1.1 degrees Celsius. This tropical stability contrasts sharply with the dramatic seasonal changes in water availability. The consistent warmth supports year-round biological activity despite the extreme wet-dry cycle that defines the landscape.
Rainfall concentration between January and May creates a pronounced rainy season that fills the lagoons, while the remaining months bring progressively drier conditions. This pattern repeats annually, creating a predictable ecological rhythm where species have adapted to exploit the temporary abundance of freshwater. The climate classification reflects tropical characteristics despite the desert-like appearance of the dunes.
Where is Lençóis Maranhenses National Park?
Lençóis Maranhenses National Park is in Brazil, South America, at 2.48°S, 43.13°W. The closest places in the Terravel atlas are Ipanema District (2,280 km), Orinoco River (2,311 km) and Iguaçu National Park (2,849 km).
Photos of Lençóis Maranhenses National Park
Photo: Paulo Cattelan · CC BY-SA 4.0
Photo: Paulo Nogueira Pires Maia · CC BY-SA 4.0
Photo: Susi Becker · CC BY-SA 4.0
Lençóis Maranhenses National Park at a glance
Questions about Lençóis Maranhenses National Park
Why do lagoons form in the dunes if the area looks like a desert?
The park receives 1,200 millimeters of rain annually, well above the 250-millimeter threshold that defines deserts. An impermeable rock layer beneath the sand prevents water from draining away, allowing it to accumulate in the valleys between dunes during the rainy season from January to June. The lagoons evaporate rapidly once the dry season begins.
How large do the seasonal lagoons grow?
Individual lagoons reach up to 100 meters in length and 3 meters in depth. Collectively, the lagoons cover as much as 41 percent of the park's total 155,000-hectare area during peak rainy season. Water temperature ranges from 27.5 to 32 degrees Celsius with low nutrient levels.
What endangered animals live in the park?
Four species appear on Brazil's endangered species list: the scarlet ibis, neotropical otter, oncilla, and West Indian manatee. The park also supports 112 bird species, 133 plant species, and at least 42 reptile species. The lagoons host fish including the wolf fish, which burrows into mud and becomes dormant during the dry season.
How did the sand dunes form?
Rivers including the Parnaíba and Preguiças carry sand from the continent's interior to the coast. Atlantic winds then push the sand back inland up to 50 kilometers, creating barchanoid dunes that rise as high as 40 meters. This wind-driven process began during the late Quaternary period and continues reshaping the landscape.
What activities can visitors do in the park?
The park receives approximately 60,000 visitors annually who engage in surfing, canoeing, and horse riding. The lagoons and beaches provide access for water-based activities, while the dunes support land-based exploration. Visitor activities must operate within the park's conservation framework protecting endangered species.
Sources and further reading
This article was written from the reference material below, retrieved and reviewed for source alignment on September 13, 2026. Use official local sources for changing access or travel information.
About this page. Terravel combines its curated place catalog with credited photography and geographic reference data. Practical travel details can change; use the linked destination guide and official local sources when planning a trip. Send a correction.
Test yourself
Which South American park transforms into an archipelago of freshwater lagoons between sand dunes during rainy season?
Lençóis Maranhenses National Park in northeastern Brazil is unique for its seasonal lagoons that form in valleys between dunes when rainwater is trapped by impermeable bedrock beneath the sand.
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