Ket (ke'tyu) [key], river, c.845 mi (1,360 km) long, W central Siberian Russia. It rises in central Siberia, just N of Krasnoyarsk, and flows NW and W into the Ob. The Ket is navigable c.410 mi (660 km). It is connected with the Kas (a tributary of the Yenisei) by the Ob-Yenisei canal system.