Its source is near the villages of Kiemėnai [lt] and Vindžiūnai [lt], 6 km south of Šumskas, nearby to the A3–M7 Medininkai–Kamenny Log border crossing complexes of the Belarus–Lithuania border for approximately 12 kilometers.

Eventually, its waters, via the Neris draining into the Neman River, reach the Baltic Sea.

[1] Vilnelė, the diminutive form of the original hydronym Vilnia, came into popular use in Lithuanian and in Soviet times largely replaced the latter because of Polish language influence — Poles translated Lithuanian name of the river with such diminutive form (Wilenka).

Within the river basin, approximately 30 living species of fish and birds have protected status.

[3] In an effort to restore the upstream migration of salmonids in the basin, a fish ladder was constructed on the Vilnia in 2000.