Ban Gioc-Detian Falls, Vietnam/China

Ban Gioc-Detian Falls on the Quay Son River straddles the border between Cao Bang Province, Vietnam, and Guangxi, China, and is Asia's largest transnational waterfall, spreading up to 208 metres wide across a multi-tiered cascade that drops 30 metres in the main section. Unlike most major waterfalls, its beauty lies as much in context as in scale: the falls tumble through a pastoral landscape of limestone karst mountains, bamboo groves, and emerald rice paddies that looks unchanged for centuries, with local farmers still working the fields in the foreground. The Vietnamese side is accessible by boat on the Quay Son River for close-up views; the Chinese side (Detian) is larger-scale and more developed. Best visited September–November at peak water volume.