The Neman, Niemen, Nyoman, Nemunas or Memel is a river in Europe that rises in central Belarus and flows through Lithuania then forms the northern border of Kaliningrad Oblast, Russia's western exclave, which specifically follows its southern channel. It drains into the Curonian Lagoon, narrowly connected to the Baltic Sea. The 937 km (582 mi) long Neman is a major Eastern European river. It flows generally west to Grodno within 12 kilometres (7.5 mi) of the Polish border, north to Kaunas, then westward again to the sea.

The Lithuania–Russia border is an international border between the Republic of Lithuania and Kaliningrad Oblast, an exclave of the Russian Federation. It is an external border of the European Union. The 274.9 km (170.8 mi) long border passes through the Curonian Spit and Curonian Lagoon, and then follows along the Neman River, Šešupė, Širvinta, Liepona, and Lake Vištytis. The sea border is another 22.2 km (13.8 mi). There is a tripoint between Lithuania, Russia, and Poland with a stone monument at 54°21′48″N 22°47′31″E.