The Pantanal is a natural region encompassing the world's largest tropical wetland area. It is located mostly within the Brazilian state of Mato Grosso do Sul, but it extends into Mato Grosso and portions of Bolivia and Paraguay. It sprawls over an area estimated at between . Various subregional ecosystems exist, each with distinct hydrological, geological and ecological characteristics; up to 12 of them have been defined (RADAMBRASIL 1982).