Pakbeng is on the Mekong river and every day tourists arrive from Luang Prabang or Thailand on the slow boat. When you arrive you climb the steps with your bag or you can get the locals to do it for at a price.
The slow boat leaves HouayXai around 10.30 AM and takes you in some 7 hours to Pakbeng.
I expected a highlight of my Laos visit but was extremely disappointed. The boat was too crowded with foreigners, we didn't have any legspace on the hard wooden benches.
We didn't stop once to visit a river village .
The boat stays in the middle of the very wide Mekong so you can't see a thing of the nearly non-existent riverlife.