The river Lukna flows in Trakai district, the river Merkys right tributary. Length of the river 32 km, the basin area 150 km ². The source at Starkiskes village, 7km southeast from Trakai town. Flows to the west through the lakes Meduvis, Karvis and Lukna, below turns to south. To the lake Meduvis called the Medrynia. Flows into the river Merkys 118 km from its mouth 12 km northwest from Valkininkai village. Average gradient 70 cm/km. Average rated discharge upstream the brook Aluona 0.41 m³/s, at the mouth 1.24 m³/s.

All year.
Water plants, low footbridges.
WW WW 0.

8.4 Bridge. Paluknys. To Madziunai village near the river forests. The riverbed channeled, width 10 m.
7.3 Small bridge.
7.2 right Podbarkai.
6.7 right Lukonis. Average gradient to brook Mamavys 82 cm/km.
4.6 Small bridge. right Madziunai.
4.3 Small bridge. right Madziunai.
4.1 Small bridge. right Madziunai.
3.9 Small bridge. right Madziunai.
3.5 Vilnius - Alytus road bridge. 40 m upstream bridge. right Madziunai. The channeled river flows through meadows, the banks bare, width 10 m.
2.9 left Mamavys. Average gradient to the mouth 79 cm/km.
2.3 Small bridge.
0.6 left Zvirgzde.
0.4 Bridge.
0.0 The Lukna flows into the river Merkys.