Starting on the China border, the Nam Ou drains all of Phongsali province and flows down through western Luang Prabang province to meet the Mekong above Luang Prabang. Much of the Phongsali province watershed is devoid of roads and still well covered with old-growth forests, and the river and its many tributaries remain in many ways as they were when nineteenth-century French explorers passed through. That said, the advent of improved roads has meant that river traffic has somewhat diminished; while this can mean that you may have to wait a few days (or charter a boat) to travel up (or down) it, it does retain an unhurried, very local charm, without the uncomfortable crowds of the more famous Mekong journey.
An important Mekong tributary, the Nam Ou holds a cherished place in Lao lore as the original route followed by Luang Prabang’s founding father, Khun Lo, and later by Fa Ngum, the warrior-king, as he headed towards Luang Prabang to claim the throne and found the Kingdom of a Million Elephants. The river begins its journey in the southern flanks of the mountains separating Laos and Yunnan in China. This northernmost part of Laos, Phongsali province, is hemmed in by high mountains on three sides, and the Nam Ou is joined by no less than eight major tributaries before entering Luang Prabang province and beginning its final run down to the Mekong. Two of these tributaries, the Nam Khang and the Nam Houn, pass within the huge Phou Den Din NBCA, along the border with Vietnam.
The main city of the upper Nam Ou is Phongsali, the provincial capital. To the east, Hat Sa effectively acts as Phongsali’s river port on the Nam Ou. The other two important towns on the Nam Ou are Muang Khoua and Nong Khiaw: Muang Khoua sits astride the river where Route 4 continues from Oudomxai to Dien Bien Phu, Vietnam, while Nong Khiaw is located where Route 1 crosses the river on its way from Oudomxai to Hua Phan province in the extreme northeast. Aside from tiny Muang Ngoi, all of the towns listed in this section can be reached by both road and river, though undoubtedly the latter is the more enjoyable option.