Ubsu-Nur, or Uvs Nuur, is a lake in a land of extremes. It lies in a closed basin on the border between Mongolia and the Russian republic of Tuva, in the middle of Central Asia, where there is no outlet to the sea, so the water simply evaporates, leaving it too salty to drink. It is the largest lake in Mongolia by area, shallow, with wide marshes and reed beds, and it sits between the Altai mountains to the west and the Sayan range to the north. The Tes river, which feeds the lake, gives its name to a part of the basin, and the whole area was listed by UNESCO in 2003 as the Uvs Nuur Basin.
What makes it special is the sheer variety packed into a small space. Within a few hours' travel you pass from desert to steppe, to mountain forest, to tundra and glaciers, and the basin is a stopping point for migrating birds, including swans, cranes and pelicans, as well as a refuge for snow leopards, argali sheep and ibex in the surrounding mountains. The winters are famously harsh, with temperatures falling below minus forty degrees, and summers can be hot, so the lake freezes solid for months.
Travelling here is an expedition. The nearest large town on the Mongolian side is Ulaangom, with fuel and basic services, but distances are huge and fuel stations are far apart outside towns. The road network consists of some paved stretches and a lot of tracks, which turn to mud after rain and drifts in winter. Carry spare fuel, food and water, a repair kit and a satellite messenger, and avoid travelling alone.
Mongolian herders live here in felt tents, called gers, with flocks of sheep, goats, horses and camels, and they will offer salty milk tea and dried curd to a visitor. Accept politely. The best season is June to September, when the steppe is green, with mosquitoes near the marshes. Cold arrives early, and in September the first snow can fall on the high ground. The sky at night, with no light for hundreds of kilometres, is the reason to stay.