The river Lokys flows in Jonava district, the river Neris right tributary. Length of the river 24 km, the basin area 120 km ². The source at Paloke village, 18 km northeast from Jonava town. Flows to the southwest. Flows into the river Neris 43 km from its mouth at Gudzioniai village, 3 km to northeast from Jonava town. Average gradient 202 cm/km. Average rated discharge at the mouth 0.63 m³/s.

At high water level. Spring flood, or after heavy rains.
Rapids, shalows, dams, strainers.
WW 0/1 (1+).

3.3 The dam of Berzai. left Jadvygava. The river flows through forest, width approx. 5 m. In the riverbed stones small rapids, strainers, can be beavers dams. The current speed average.
1.8 Kaunas - Ukmerge highway bridge. Under the bridge the river flows through concrete pipe.
1.4 Small bridge.
1.3 The pond begins.
0.8 The dam right Gudzioniai. left hillfort Lokeneliai (Zvalgakalnis). right hillfort Gudzioniai.
0.0 The Lokys flows into the river Neris.