The river Mera - Kuna flows in Svencionys district, the river Zeimena left tributary. Length of the river 58 km, the basin area 206 km ². The source 5 km northeast from Svencionys town. Flows to west and southwest through Svencionys town. Upstream to the lake Kuna calls the Kuna. Flows into the river Zeimena 29 km from its mouth 7 km northeast from Pabrade town. Average gradient 132 cm/km. Average rated discharge at the mouth 1.94 m³/s.

All year.
Strainers, low footbridges.
WW 0 (1-).

21.8 Zalavas - Vincentavas road bridge. right Zalavas. The river channalized, width 10 m.
20.4 Cannalized section of the river ends. The river meanders through forests. The banks mostly steep, up to 15 m height. The river width 7-10 m, speed of current average. Strainers.
19.5 left Merionys. right Pamerionys.
19.2 Low bridge. Not navigable, portage is needed. left Merionys. right Pamerionys.
17.7 right hill fort Baliuliai.
17.5 Railway bridge.
16.6 left Baliuliai.
15.6 Pabrade - Svencionys road bridge.
14.5 Accross the river high-voltage line.
13.9 right Kalviske.
13.4 left Padvare.
10.4 Bridge. Guziai. The number of strainers decreases.
9.4 Bridge. Guziai.
8.7 left Guziai. The river flows through forest.
7.3 right the brook.
3.0 bridge.
1.9 Railway bridge. A bit downstream bridge. The number of strainers decreases. left Pazeimene.
0.0 The Mera flows into the river Zeimena.