Largest tributaries
Perciformes - Perches
Salmoniformes - Salmons and Trouts
Esociformes - Pikes
Cypriniformes - Carps
Acipenseriformes - Sturgeons and Paddlefish
Scorpaeniformes - Mail-cheeked fishes
Gasterosteiformes - Sticklebacks
Gobiiformes - Gobies
The Ob is a major river in Russia. It is in western Siberia; and together with Irtysh forms the worlds seventh-longest river system, at 5,410 kilometres (3,360 mi). It forms at the confluence of the Biya and Katun which have their origins in the Altai Mountains.
It is the westernmost of the three great Siberian rivers that flow into the Arctic Ocean (the other two being the Yenisei and the Lena). Its flow is north-westward, then northward then these directions are repeated over greater distance.
The main city on its banks is Novosibirsk, the largest city in Siberia, and the third-largest city in Russia. It is where the Trans-Siberian Railway crosses the river.
The Gulf of Ob is the worlds longest estuary.
