Ban Gioc – Detian Falls (Chinese: 德天瀑布 & 板約瀑布 - Vietnamese: Thác Bản Giốc & Thác Đức Thiên) are 2 waterfalls on the Quây Sơn River or Guichun River straddling the Sino-Vietnamese border, located in the Karst hills of Daxin County, Guangxi (Chinese side), and in the district of Trung Khanh District, Cao Bằng province on the Vietnamese side, 272 km (169 mi) north of Hanoi.[Ref 1]
The waterfall drops 30 m (98 ft). It is separated into three falls by rocks and trees, and the thundering effect of the water hitting the cliffs can be heard from afar.[Ref 2]
It is currently the 4th largest waterfall along a national border, after Iguazu Falls, Victoria Falls, and Niagara Falls and was one of the crossing points for China’s army during the brief Sino-Vietnamese War. Nearby there is the Tongling Gorge accessible only through a cavern from an adjoining gorge. Rediscovered only recently, it has many species of endemic plants, found only in the gorge, and in the past was used as a hideout by local bandits, whose treasure is occasionally still found in the cliff-side caves.