The Budreg Del sand Is the northernmost sand massif, not only In Mongolia, but the world and It Is 180 km In length and 40-45 km wide. The sand massif covers the area from the south shore of Uvs Lake to the Tes River, In western Mongolia. The north edge of the sand Is the south bank of the Nariinii River. Buurug Del Els sand covers an area of 3800 square km and it is recognized as the biggest In Mongolia. It equals 23.1 % of the total sand of the Great Lakes Basin. Buurug Del sand massif consists of the West and the South parts and Altan Els sand. The western and southern part are separated by Bayan Khairkhan Mountain (2273 m) and Bayan Lake, while the south part Is separated by Khar Mod grove from Altan Els sand. The west part is hillock sand while the south part and Altan Els sand are hollow-hillock. Altan Els Is part of the Uvs Lake Strictly Protected Area. The sand thickness differs: It is more than 100 m In the south part of the Uvs Lake basin while the thickest is 50-60 m around the beginning of the Nariin River, and Khulst River which flows into Bayan Lake. The middle area of the Buurug Del Sand has no surface water, but surrounding areas have some small rivers and lakes. The fresh water lake of Bayan Nuur is 10 km from Zuun Gobi soum at 932 m above sea - level and is surrounded by Buurug Del sand. At the beginning of Nariin River, there is a small river that begins from the Bayan Lake. Duruu Lake is located west of Altan sand and on the border of Mongolia and Russia. Buurug Del Els become smaller sand dunes, 2-8 m in height, at the southern part but become larger again around Tsagaan Usnii Am and end of Tes River Valley. Dune hills are on average 140-300 m long and 20 m high. Many species of medicinal herbs grow in Buurug Del band like ouch grass, worn wood, thyme, peach grass, redcurrant, alfalfa, artemisia, tumbleweed, wild leek and bush plus some kinds of trees in north of the Agartag Mountain like pine-tree, larch, asp and wiker. Some sea-buckthorns grow alongside the river Tsagaan Usnii Am, Altan sand. This is also the home of fox, maskdeer, manulcat, rabbit, jerboa, wild mouse, souslik, two kinds of lizards, and also some species of birds such as pallas sandgrouse, partridge , hazel hen, magpie, cuckoo and beetle.