You can arrange rafting or canoeing trips down Nakon Nayok River from either Wang Takhrai or from the bridge at Klong Tha Dan.
You will follow your tributary and see it merge with a few others to slowly form the Nakon Nayok River. The waterways are quite narrow at some points so larger boats cannot make the journey. There are a few gentle rapids but nothing very scary. There are many twists and turns as the streams meander through the peaceful Nakon Nayok countryside. You can slip off the boat for a swim in the river as you go. It all makes for a very pleasant couple of hours entertainment.
You can rent a kayak to paddle around the local vicinity for 150-baht an hour. It costs more to arrange a trip down the river with a pick up at the other end. A rafting trip for 6 people with a guide and collection at the other end will cost around 1,500 baht.