The Sinyaya (Russian: Синяя, Belarusian: Сінюха, Latvian: Zilupe) is a river in Verkhnyadzvinsk Raion of Vitebsk Region of Belarus, in Zilupe, Ludza, and Cibla municipalities of Latvia, and in Sebezhsky, Krasnogorodsky, and Ostrovsky Districts of Pskov Oblast in Russia, part of the Baltic Sea basin.

[1] Its source of the Sinyaya is Lake Osveya, Belarus, close to the place where the borders of Belarus, Latvia and Russia meet.

It further departs from the border into the Latvian side, and flows through the town of Zilupe.

Even further north, the river turns northeast and enters Russia.

It flows through the urban-type settlement of Krasnogorodsk and turns east in the selo of Venyavino.