The بحیرہ قزوین is generally regarded by geographers, biologists and en:limnologists as a huge inland en:salt lake. However, the Caspian's large size means that for some purposes it is better modeled as a sea. Geologically, the Caspian, Black, and Mediterranean seas are remnants of the ancient en:Tethys Ocean. Politically, the distinction between a sea and a lake may affect how the Caspian is treated by international law.
