A fisherman tries his luck on the Sava River in the Slavonian town of Županja. Sava flows through Slovenia, Croatia and Serbia, discharging into the Danube in Belgrade. Its central part is a natural border of Bosnia-Herzegovina and Croatia. The Sava forms the northern border of the Balkan Peninsula, and the southern edge of the Pannonian Plain.
The Sava is 990 kilometres (615 miles) long, including the 45-kilometre (28 mi) Sava Dolinka headwater rising in Zelenci, Slovenia. It is the greatest tributary of the Danube by volume of water, and second-largest after Tisza in terms of catchment area (97,713 square kilometres) and length. Sava is one of the longest rivers in Europe and among a handful of European rivers of that length that do not drain directly into a sea.
The population in the Sava River basin is estimated at 8,176,000, and it connects three national capitals—Ljubljana, Zagreb and Belgrade. The Sava is navigable for larger vessels from the confluence of the Kupa River in Sisak, Croatia, approximately two-thirds of its length.