Ob, ob, awb or ohb, River is one of the chief rivers of Russia in Asia. It rises in the Altai Mountains of western Siberia and flows northwest for 2,268 miles (3,650 kilometers) before it empties into the Kara Sea through the Gulf of Ob (Obskaya Guba). The river drains about 1,130,000 square miles (2,930,000 square kilometers).