The Oka River
Oka River, a river in western Russia. It is 940 miles (1,513 km) long. From its source in the Central Russian Uplands, the river flows generally northward to Nizhniy Novgorod, where it joins the Volga River.

Oka River, a river in western Russia. It is 940 miles (1,513 km) long. From its source in the Central Russian Uplands, the river flows generally northward to Nizhniy Novgorod, where it joins the Volga River.