<Tr> <Td> - min </Td> <Td> 2,360 m / s (83,343 cu ft / s) </Td> </Tr> <Tr> <Td_colspan="2"> Map of the Ob River watershed </Td> </Tr> <P> The Ob River (Russian: Обь, IPA: (opj)), also Obi, is a major river in western Siberia, Russia, and is the world's seventh - longest river . It forms at the confluence of the Biya and Katun Rivers which have their origins in the Altay Mountains . It is the westernmost of the three great Siberian rivers that flow into the Arctic Ocean (the other two being the Yenisei River and the Lena River). </P> <P> The Gulf of Ob is the world's longest estuary . </P>

Where does the ob river start and end
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