The Pantanal is the largest wetland in the world, covering more than 365,00 kilometers of the central floodplains of Brasil, Bolivia, and Paraguay. This fragile ecosystem, dependent upon critical habitats and the flood cycle, is under threat from the silt runoff of deforested highlands and efforts by man to make the area navigable. This assessment, which discovered new species in the area, examines previously unexplored regions of the Pantanal—essential sanctuaries for migratory birds, critical nursery grounds for aquatic life, and refuges for such creatures as the black caiman, deer, and jaguar.