Lake Teletskoye is the largest lake in the Altai Mountains and the Altai Republic, Russia, and has depth up to 325 meters.

The Altai Republic, also known as Gorno-Altai Republic, and colloquially, and primarily referred to in Russian to distinguish from the neighbouring Altai Krai as the Gornyi Altai, is a republic of Russia located in southern Siberia. The republic borders the Russian federal subjects of Kemerovo Oblast to the north, Khakassia to the northeast, Tuva to the east, Altai Krai to the west, as well it borders three countries: Mongolia to the southeast, China to the south and Kazakhstan to the southwest. It is a part of the Siberian Federal District, and covers an area of 92,903 square kilometers (35,870 sq mi), with a population of 210,924 residents. It is the least-populous republic of Russia and least-populous federal subject in the Siberian Federal District. Gorno-Altaysk is the capital and the largest town of the republic.