The largest rivers in Slavonia are found along or near its borders—the Danube, Sava and Drava. The length of the Danube, flowing along the eastern border of Slavonia and through the cities of Vukovar and Ilok, is , and its main tributaries are the Drava and the Vuka. The Drava discharges into the Danube near Aljmaš, east of Osijek, while mouth of the Vuka is located in Vukovar. Major tributaries of the Sava, flowing along the southern border of Slavonia and through cities of Slavonski Brod and Županja are the Orljava flowing through Požega, and the Bosut—whose course in Slavonia takes it through Vinkovci. There are no large lakes in Slavonia. The largest ones are Lake Kopačevo whose surface area varies between , and Borovik Reservoir covering . The Lake Kopačevo is connected to the Danube via Hulovski canal, situated within the Kopački Rit wetland, while the Lake Borovik is an artificial lake created in 1978 in the upper course of the Vuka River.