About 1 kilometer north of the place where boats to see the dolphins leave, are the Kampi Rapids where you can relax, swim and enjoy the rapids.
There is a huge picnic spot, very popular with the locals: bamboo structures with a straw roof built out over the river. Some are hundreds of meters long and all are lined with hammocks. You will see local families with large supplies of fruit, vegetables, fish, rice, cooking utensils and beer, enjoying their free time.
Do as they do, climb into a hammock and while away, or jump into the river (NOT in the rainy season, when water levels are high and the flow is strong and fast!).