Thang Hen Lake is located in Quoc Toan Commune, Tra Linh District. Being at the height of 1,000m above the sea level, Thang Hen Lake is one of 36 beautiful lakes in the mountains of Vietnam.
In the mass of mountains appears beautiful scenery with rows of trees rising from steep cliffs and reflecting themselves on the very blue water surface which curves round the heart of a valley with rough subterranean rocks.
The lake has basin shape with the length of over 500m and the width of 300m. On the other side of the lake is a large cave from which a water source runs out days and nights. Everyday, tide goes up and down twice. In rainy season, while the other lakes bear red-water, the water in Thang Hen Lake still be clear and blue. In dry season, the lowest water level is about 10 meters.
Near by Thang Hen Lake is Thanh Luong lake, in the middle of which rises a very beautiful mountain. Nowadays, Thang Hen Lake becomes a convalescence and ecological tourism.
From Cao Bang Town, go to Hoa An District (19km) by the Nation Road 3, turn left along Road 205 for about 5km, then turn left 3-4km to reach Thang Hen Lake, east of Cao Bang Province.