Quay Son is a beautiful jade-blue river that feeds the majestic Ban Gioc waterfall. The river has a total lenght of 89km and flows at an altitude of around 550m. The river originates from China and constitutes the border to Vietnam in the area of Ban Gioc waterfall. The winding river flows through a spectacular scenery of green rice terraces and limestone mountains. A good way to explore the river is taking a boat trip by canoe or kayak.