- This artificial lake has an area of 23,400 ha and 1,331 islands and hills with diverse ecological environments. The water in the lake is blue and clear, and imprinted with the reflections of the surrounding ancient forest. The thousands of hills and islands feature caves such as the Hum, Cau Cuoi and Bach Xa. The Thac Ba Temple always draws visitors. Thac Ba Lake is not only a beautiful..