NASA Earth Observatory reported on August 5, 2026, that a Landsat 9 image captured on June 8, 2026, showed hundreds of freshwater lagoons partially filling troughs around many dunes in Lençóis Maranhenses National Park in northeastern Brazil. The park receives about 125 centimeters (50 inches) of rain per year, the agency said, and its white quartz dunes rise as much as 30 meters (100 feet).

The dune field spans about 900 square kilometers (350 square miles). NASA said a partly impermeable layer of bedrock and clay beneath the sand keeps lagoons from draining in the wet season; as rains subside between August and November, the water table falls, and by December most lagoons dry up. Satellites showed the field extended westward by about 0.5 kilometers between 1986 and 2026 in some areas, the agency said.

UNESCO designated the park a World Heritage site in 2024. NASA said it hosts more than 850 documented species, including four endangered ones: the neotropical otter, West Indian manatee, scarlet ibis and oncilla.