Wanderlust World Wanderlust World There is no single river named "Ob-Irtysh." Rather, the Ob River and the Irtysh River are two distinct but interconnected major rivers flowing through Russia (with the Irtysh originating in China and flowing through Kazakhstan before entering Russia). Together, they form one of the world's longest river systems.
The Ob River flows entirely within Russia, rising in the Altai Mountains of southern Siberia and coursing north and west for approximately 3,650 km (2,268 miles) to the Gulf of Ob, a vast estuary of the Kara Sea (Arctic Ocean). It's Russia's fourth-longest river and a vital transportation artery for western Siberia.
The Irtysh River is the Ob's principal tributary—and remarkably, longer than the Ob itself at 4,248 km (2,640 miles). It originates in the Altai Mountains of China's Xinjiang region, flows northwest through Kazakhstan (where it's known as the Ertis), and enters Russia before joining the Ob near Khanty-Mansiysk. The Irtysh is the longest tributary river in the world.
When measured from the Irtysh's source to the Ob's mouth, the Ob-Irtysh system spans ~5,410 km (3,360 miles), ranking as the seventh-longest river system globally. This vast watershed drains much of western Siberia, supporting:
The hyphenated name "Ob-Irtysh" sometimes appears in hydrological literature to denote the entire river system from the Irtysh's headwaters to the Arctic Ocean. But on maps and in geography, they remain two named rivers—one a tributary of the other—both flowing predominantly through Russian territory.