The Oka river has its source in the central Russian Upland. With a total length of 1490 km, it is the largest right tributary of the Volga. At the confluence with the Volga it meets the city of Nizhny Novgorod.
Avastatud: 22-9-1990 Avastamiskoht: La Silla Avastajad: Elst, E. W.