Ban Gioc is one of Vietnam’s best-known waterfalls, and its image adorns the lobby of many a cheap guesthouse. The falls, fed by the Quay Son River that marks the border with China, are an impressive sight in a highly scenic location. Aim to visit around lunchtime when the upstream dam is opened to allow full flow.
Boat owners here will punt you on bamboo rafts (50,000d) close enough to the waterfall so you can feel the spray on your face. Rafts on the Vietnamese side have blue canopies; on the Chinese side canopies are green.
For a fine overview of the falls and the entire karst valley, head back towards Cao Bang for 1km and climb left to the hillside Phat Tich Truc Lam Ban Gioc Pagoda.
The police station at the waterfall sometimes requires foreigners to buy a border permit (200,000d for up to 10 people) to visit the falls, though we weren't asked during our recent visit. Bring your passport just in case.