Thac Ba Lake is one of three Vietnam's largest artificial lakes and famous for the first hydro power plant. Thac Ba Lake is also well-known for its eco-system site. Thac Ba Lake was built in 1970 by the construction of a dam on the Chay River. Thac Ba reservoir covers a total area of 23.400 ha, of which 19.05 ha is water area and the remaining 4.35ha of islets on the Reservoir. This artificial lake has 1,331 islands and hills with various ecological environments. The water in the lake is imprinted with the reflections of the surrounding ancient forest creating a blue and clear background of the water.