The stretch of Mekong between Stung Treng and the Laos border is rich in ecotourism potential, most of it still largely untapped. River islands, waterfalls, rapids and impressive stretches of flooded forest dot the waters, culminating in the thundering Sopheak Mitt waterfalls, which block the route on into Laos.
As at Kratie, pods of Irrawaddy dolphins are the major draw, and can be found at several spots along the river. Most visitors head for the so-called Anlong Cheuteal dolphin pool, just south of the Laos border. Boat trips here can be arranged at Stung Treng; alternatively, you may be able to arrange a boat (roughly $15/hr) at the nearby villages of O Svay and Preah Rumkel – homestays can also be arranged at the latter. Dolphin numbers are smaller here than at Kampie, although there’s still around a ninety percent chance of spotting them.