Ust-Sema is a small village on the Katun river in the Altai Republic, where the river is swift, loud and a startling turquoise. The name means mouth of the Sema, and refers to the smaller river that joins the Katun here. It lies on the Chemal road, a few dozen kilometres south of Gorno-Altaysk, in the foothills of the mountains that form the heart of southern Siberia. The air is fresh and the forest is thick with larch and birch, and behind everything the high peaks stand in layers.
The Katun is the main river of the Altai and starts at a glacier below Belukha, the highest peak in Siberia at 4,506 metres, and the water here is cold and mineral-rich, with a colour that comes from fine glacial silt suspended in it. It runs through a deep, forested valley with rapids, pools and gravel banks, and the sound of it can be heard from the road. The surrounding mountains are part of the Golden Mountains of Altai, a UNESCO World Heritage Site for their rich variety of habitats and the importance of the region in the history of Central Asia.
Chemal, a little way upstream, is the best-known place in this stretch of the valley. A small hydroelectric station sits on the river, and a famous footbridge leads to Patmos, a rocky island in the Katun with a little church on its summit, reached by a swaying suspension bridge. The island is a popular place for visitors, with a view up and down the river. Beyond is the beginning of the true mountain landscape.
The road here follows the river through a series of bends and short climbs, with the Katun alongside, and gives some of the finest riding in southern Siberia, with smooth asphalt in places and rough patches in others. Traffic can be heavy in summer, when visitors from Novosibirsk and Barnaul flood the valley, so go early. Cattle and horses wander across the road in the villages, and watch for rockfall after rain.
Services are modest. Fuel is in Gorno-Altaysk and some larger villages, and it is wise to top up there. In the villages there are small cafés and roadside stalls selling honey, dried fruit and fresh bread, and the local food includes river fish and mutton. The best months are June to September, and autumn colours can be glorious in late September.