The Spree is, with a length of approximately 400 kilometres, the main tributary of the River Havel, and at their confluence in Berlin-Spandau, is much longer than the Havel, which itself flows into the Elbe at Havelberg. The river rises in the Lusatian Highlands, that are part of the Sudetes, in the Lusatian part of Saxony, where it has three sources: the historical one called Spreeborn in the village of Spreedorf, the water-richest one in Neugersdorf, and the highest elevated one in Eibau. The Spree then flows northwards through Upper and Lower Lusatia, where it crosses the border between Saxony and Brandenburg. After passing through Cottbus, it forms the Spree Forest, a large inland delta and biosphere reserve. It then flows through Lake Schwielochsee before entering Berlin, as Müggelspree.
The Spree is the main river of Berlin, Brandenburg, Lusatia, and the settlement area of the Sorbs, who call the River Sprjewja. For a very short distance close to its sources, the Spree constitutes, as Spréva, the border between Germany, and the Czech Republic. The Spree's longest tributaries are Dahme and Schwarzer Schöps, other well-known tributaries are Panke and Wuhle.