North Thailand has many small and big wonderful waterfalls. They are always beautiful and impressive places. Doi Inthanon National Park is very well known for its falls such as Mae Klang, Mae Ya, Mae Pan and Vachirathan. Ofcourse these are most impressive in the rainy season. Most of North Thailand is mountainous so you can expect to find waterfalls at lots of places. Our favourite waterfalls are the thundering Vachirathan and the Mae Pan falls. Mae Pan is not often visited but it is the highest in Doi Inthanon National Park. Mae Ya falls is a bit out of the way but also worth visiting.
Also the Mae Kampong area has some nice small falls. The Mae Wang National Park has also pleasant falls where you have a dip after your trekking. Another falls that is very popular on trekking routes is the Mork Fah Falls which is within the boundary of Huay Nam Dang National Park.