Ba Bể Lake, located in Nam Mẫu commune, Ba Bể district, Bac Kạn Province in the Northeast region of the country, is the largest natural lake in Vietnam.
Having been formed approximately 200 million years ago, the lake is surrounded by limestone cliffs, which in turn are covered by primary forests. The lake comprises three zones named Pé Lầm, Pé Lù, and Pé Lèng. Three rivers, named Năng, Tả Han, and Nam Cường, are the main inflows of the lake. The Năng river enters the lake through a large waterfall called Dau Đẳng.