Largest tributaries
Perciformes - Perches
Salmoniformes - Salmons and Trouts
Esociformes - Pikes
Cypriniformes - Carps
Acipenseriformes - Sturgeons and Paddlefish
Gadiformes - Cods
Scorpaeniformes - Mail-cheeked fishes
Gobiiformes - Gobies
The Oka is a river in central Russia, the largest right tributary of the Volga. It flows through the regions of Oryol, Tula, Kaluga, Moscow, Ryazan, Vladimir and Nizhny Novgorod and is navigable over a large part of its total length, as far upstream as the town of Kaluga.
Its length is 1,500 km (930 mi) and its catchment area is 245,000 km2 (95,000 sq mi).
The Russian capital Moscow sits on one of the Oka’s tributaries – the Moskva.
