Overview
The river decided where Hue was built: the citadel faces it because geomancy required water in front of the seat of power, and the tombs of the emperors were sited along it upstream so that each could be reached by boat. A day on the water covers Thien Mu Pagoda and two or three tombs, which is a slower and better way to see them than a car tour. The boats are family-owned and the trade has been in the same families for generations.
Highlights
Agree the route and the price before boarding; the boats are hired whole rather than per seat. The morning run upstream is cooler and the light better on the return. If you only have an hour, the short trip to Thien Mu and back is worth taking on its own.