Yakutsk (Якутск) (pop. 187,000), is a city in central Siberia. It is the capital of Sakha Republic (formerly the Yakut Autonomous Soviet Socialist Republic), Russia and a major port on the Lena River.

It is also a highway center and has tanneries, sawmills, and brickworks. Yakutsk was founded in 1632 as a Cossack fort but did not grow into a city until the discovery of large reserves of gold and other minerals in the 1880s and 1890s. These reserved were developed extensively during the industrialisation under Stalin and the rapid growth of forced labour camps in Siberia also encouraged Yakutsk's development. The city has a university (founded 1956) and a branch of the Russian Academy of Sciences, which contains the noteworthy Permafrost Research Institute developed with the aim of solving the serious and costly problems associated with construction of buildings on frozen soil, which is having serious and dangerous effects within the city even today.

The Lena River runs through the city, and in the summer there are boats sailing along the river to the Trans-Siberian Railway. There are also very expensive cruises downriver offered by the remains of Intourist which visit spectacular scenery in extremely remote areas near the Arctic Ocean.

Yakutsk is one of the coldest cities on earth, with January temperatures regularly remaining below −50 °C (−58 °F). The coldest temperatures ever recorded outside Antarctica occur in the basin of the Yana River to the northeast. Yakutsk is consequently the only sizeable city built on continuous permafrost, and this has had destructive consequences because building on permafrost is in many ways similar to building on ice. The heat stored in the buildings has thawed the frozen soil below and most houses in the city today appear to stand at odd angles: in fact, they clearly are collapsing.

This city was referenced in the New York Times Crossword of Saturday, November 20th, 2004. Also referenced in the International Herald Tribune, Saturday, January 31st, 2004.