The longboat ride up the Temburong River from Bangar to the edge of the national park is one of those journeys where the travel itself justifies the trip. The boats are narrow, covered craft that move quickly through brown jungle water, past overhanging vegetation, water monitor lizards basking on the banks, and occasional proboscis monkeys in the trees. The river narrows and shallows as you head upriver; in dry season the boatmen sometimes have to pole through shallow sections.
The journey takes 30–45 minutes each way and operates as part of all tour packages into Ulu Temburong. There is no independent boat service — you need to be part of a tour, which is the main logistical constraint. The return journey downstream is faster and gives different views as the forest angles shift.