The Tarvasjõgi begins near the Piibe Highway (a historic road that connects Tallinn and Tartu).

This place is located in the Lääne-Viru County, south of Jäneda and Kõrveküla in Tapa Parish.

In the village of Mõnuvere, it turns northwest and reaches Põhja-Kõrvemaa Nature Reserve, which it flows through for the rest of its course.

The land has extensive lakes, bogs, eskers, sand and gravel kames, fens, and heaths, with 40 percent forest cover.

It provides a habitat for wolves, Eurasian lynx, and brown bears, and protected bird species include black storks, golden eagles, western capercaillies, and common cranes.