Kupa

The Kupa (Croatian pronunciation: [kûpa]) or Kolpa (Slovene pronunciation: [ˈkóːlpa] or [ˈkóːwpa]; from Latin: Colapis in Roman times; Hungarian: Kulpa) river, a right tributary of the Sava, forms a natural border between north-west Croatia and southeast Slovenia. It is 297 kilometres (185 miles) long, with a length of 118 km (73 mi) serving as the border between Croatia and Slovenia and the rest located in Croatia.