The Reiu is a long river in southwest

Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a ...

. Its source is Soka Lake in

Latvia Latvia ( or ; lv, Latvija ; ltg, Latveja; liv, Leţmō), officially the Republic of Latvia ( lv, Latvijas Republika, links=no, ltg, Latvejas Republika, links=no, liv, Leţmō Vabāmō, links=no), is a country in the Baltic region of ...

. It flows generally north. It is a

left tributary A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage b ...

of the

Pärnu River Pärnu () is the fourth largest city in Estonia. Situated in southwest Estonia, Pärnu is located south of the Estonian capital, Tallinn, and west of Estonia's second largest city, Tartu. The city sits off the coast of Pärnu Bay, an inlet o ...

into which it flows near the city of Pärnu. The basin area of Reiu is 917 km² and average discharge 17.3 m³/s.

References

Rivers of Estonia Rivers of Latvia Landforms of Pärnu County International rivers of Europe {{Latvia-river-stub