Yakutsk (yəkōtskˈ) [key], city (1989 pop. 187,000), capital of the Sakha Republic, E Siberian Russia, a major port on the Lena River. It is also a highway center and has tanneries, sawmills, and brickworks. Yakutsk was founded in 1632. It has a university (founded 1956) and the Yakutsk branch of the Russian Academy of Sciences.