Ubsunur Hollow (also spelled Uvs Lake Basin; Mongolian: Увс нуурын хотгор) is a fragile mountain endorheic basin or depression located on the territorial border of Mongolia and the Republic of Tuva in the Russian Federation, named after Uvs Lake, a large, shallow and very saline lake in the basin's center. Several smaller lakes are scattered throughout. It is part of a combination of raised lands and depressions located throughout the Tannu-Ola and Altai mountainous regions. Here, the world's most northern desert meets the northern hemisphere's most southern tundra zone.