Southeast Asia forum

From my knowledge you'd have to head a ways south of Tiger Leaping Gorge to pick up a pleasantly navigable portion of the Mekong - at least south of the Man Wan Damn which is south of Dali. During the rainy season of May to October you would find the Mekong a little beastly even down near Jinghong so it depends on when you are traveling as well - it'd have to be the winter if you want to get into the river anywhere north of the Lao-China border. Along with that - everything I've heard over the last several years is that China has tightened up the river boarder crossing and doesn't allow tourists to take boats, its very difficult to get a captain to take you passed the border as they risk loosing their boat if caught.

For an adventure you could take the long route through from Dali to Jinhong on local buses and stop at towns along the way in Baoshan. From Jinhong you can try to see if the boat crossing rules have changed (as the people at Meimei Cafe always keep updated on it) but may end up having to do an overland crossing - after which you can pass through Luang Nam Tha and then hit the river near Huay Xai.