The Olm , or Proteus ( Proteus anguinus ) is a strange and obscure amphibian , native to the underground waters of the Dinaric karst that flow through the SoÄ a river basin near Trieste in Italy , through to southern Slovenia , southwestern Croatia , and Herzegovina . The Olm , or Proteus ( Proteus anguinus ) , is a blind amphibian endemic to the subterranean waters of caves of the Dinaric karst of southern Europe . It lives in the waters that flow underground through this extensive limestone region including waters of the SoÄ a river basin near Trieste in Italy , through to southern Slovenia , southwestern Croatia , and Herzegovina .