The Obinitsa (also known as the Tuhkvitsa) is a stream in the rural municipality of Meremäe that flows into the Piusa River.

The stream flows entirely through Meremäe and passes the Obinitsa Reservoir.

The villages of Tepia, Serga, Tobrova, Lepä, and Obinitsa are located along the stream.

[1] There were eight water-powered mills on the Tuhkvitsa: Serga, Tepia, Lepa, Tobrova, Porga, Kruuse, Sonne, and Ala-Tsumba.

The banks of the upper reaches of the stream are shallow and border on farmlands and meadows, but from the Kruuse Mill onward a deep natural valley has formed and the banks are mostly covered in alder.