The Pantanal is the largest wetland in the world, covering more than 365,000 kilometres of the central floodplains of Brazil, Bolivia and Paraguay. Its fragile ecosystem is threatened by silt runoff from 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.