The Nho Que River runs at the base of the Ma Pi Leng canyon, several hundred metres below the road that traverses the pass above. The water is an extraordinary shade of turquoise-green, the product of mineral runoff from the limestone bedrock, and the colour intensifies during the dry season when the river runs shallow and clear. From the road above, the river is a thin bright thread at the bottom of a vertical gorge; from the river itself, the walls feel almost suffocating.
Boat trips operate from a small dock below Meo Vac town, following the river upstream through the canyon. The boats are small wooden vessels operated by local families, and the trip takes about an hour each way depending on water levels. The inner canyon sections — where the walls narrow and the light falls in strips — are among the most dramatic river scenery in northern Vietnam. You cannot reach these sections on foot.