Ob

Major river in Asian Russia, flowing 3,380 km/2,100 mi from the Altai Mountains through the western Siberian Plain to the Gulf of Ob in the Kara Sea (an inlet of the Arctic Ocean). With its main tributary, the Irtysh, the Ob is 5,600 km/3,480 mi long, and drains a total area of 2,990,000 sq km/1,150,000 sq mi.

Although frozen for half the year and subject to flooding, the Ob is a major transport route. It is chiefly used for transporting the natural gas and oil extracted in the region, along with timber, grain, peat, and coal. Novosibirsk and Barnaul are the main ports on its banks.