shallow lake on the boundary between Siberia (Russia) and China. Most of the lakeshore is in Primorsky kray (region) of Russia; the northern shore is in Heilungkiang sheng (province), China. Much of the lake is surrounded by swampland; it varies in area from about 1,500 to 1,700 square miles (4,000 to 4,400 square km). Around the southern end is the Khanka Lowland, a rich black-earth area with some of the best soils in eastern Siberia. Lake Khanka's outlet is the Sungacha River, a tributary of the Ussuri.