There are six majordrainage basins in Lithuania: the riversNeman (Lithuanian:Nemunas),Lielupe,Venta,Daugava,Pregolya, and a strip along theBaltic where rivers flow directly into the sea.[1]

TheNeman River, which drains into theBaltic Sea, drains 42,970 square kilometres within Lithuania (65.9% of its area).[1] The river rises inBelarus, southeast of Lithuania, and receives waters from theŠešupė River, which rises inPoland.

TheLielupe River basin encompasses 10,690 square kilometers within Lithuania.[1] The Lielupe flows northward intoLatvia and into theGulf of Riga, a bay of the Baltic Sea. Its tributaries include three rivers that rise in Lithuania (theSvete,Mūša, andNemunėlis (Mēmele)).[1]
TheVenta River rises in Lithuania, flows northward into Latvia, and discharges into the Baltic. It drains 5,930 square kilometers within Lithuania.[1]
ThePregolya River (also known as the Pregel) flows in southwestern Lithuania near its border with theKaliningrad Oblast, later entering the Baltic via theVistula Lagoon. Its basin includes 70 square kilometers of Lithuanian territory.[1]
2,870 square kilometers of the country’s area drain directly into the Baltic.[1]