The Ubsunur Hollow (Uvs Lake Basin) is a fragile area in the east of the Mongolian Lake Uvs on the territorial border of Mongolia and the Republic of Tuva in the Russian Federation. It is situated within the Tannu-Ola mountain area.
The Uvs saline lake is covering 3'350 square kilometres at 759 m above sea level. It is the largest lake in Mongolia. A very small part of the northeastern end is situated within the Russian Tuva Republic.
The Tannu-Ola mountains stretches for about 560 km from the Russian Altai in the Tuva Republic in west-east direction north of the lake Uvs along the Russian-Mongolian border. Its highest summit is known as Dzhakul (Tuva Republic, Russia) and reaches an altitude of 2'930 metres.
Russia 2013, "Ubsunur Hollow Biosphere Reserve".