the tannu-ola mountains form the northern border of ubsunur hollow. , the only freshwater lake of the basin, lies, like uvs lake, on the russian-mongolian border. the more eastern part of the uvs lake drainage basin extends, in the north, to the sengilen ridge of the sayan mountains, and in the east, to the basin of sangiin dalai lake. the southern part of the hollow is bordered by the basin of khyargas lake, with the khan khökhii mountains separating both basins of the great lakes depression. more to the east, the forms the southern border of uvs lake's drainage basin. west of the uvs lake basin lies the endorheic basin of üüreg lake, bordered by the altai mountains. the separates, in part, the uvs and üüreg lake basins. the south-western tip of the uvs lake basin covers most of the range, and includes the north-eastern slopes of