pantanal (pəntənälˈ) [key], lowland region of SW Mato Grosso state, Brazil, bordering the Paraguay River and extending to the the western edge of the Brazilian Plateau. Parts of the pantanal extend into Bolivia and Paraguay. It is the world's largest wetland area, c.77,000 sq mi (200,000 sq km). Although subject to annual flooding, it is not a marshland; the water is not stagnant, and there is no malaria. The pantanal completely dries out at the end of the six-month rainy season, leaving lush grasslands that are used for cattle grazing. Millions of migratory birds visit the area every year and over 100 species of mammals and reptiles live there. However, the pristine nature of the pantanal is threatened by encroaching ranching and agriculture, poaching, and coal mining.