The Merkys is a river in southern Lithuania and northern Belarus. It flows for 13 km (8 mi) through Belarus, 5 km (3 mi) along the Belarusian–Lithuanian border, and 195 km (121 mi) through Lithuania before joining the Neman River near Merkinė. Merkys is mostly fed by underground streams and therefore is cooler during summers and has smaller fluctuations in water level than other rivers in Lithuania.