Deep in the heart of the Khangai Mountains lies this exquisitely beautiful freshwater lake, formed millions of years ago when lava flows blocked the Suman River, a tributary of the Chuluut. The best views over Terkhiin Tsagaan Nuur (literally ‘Great White Lake’) and its epic hinterland are to be had from the rim of an extinct volcanic crater at the eastern end of the lake – the Khorgo. Yurt camps strung along the northern shore provide idyllic bases from which to ride on horseback into the surrounding grassland.