Wiang Kosai is the first national park in Prae Province. It covers Long District and Wang Chin District, Prae Province and Tern District, Sobprab District and Mae Ta District, Lampang Province. There are crossed over by high steep mountains and many beautiful waterfalls, e.g. Mae Koeng Luang, Mae Koeng Noi, and also Mae Jork Hot Spring which is the source of rivers and streams. The area of the park is about 410 Km2 (256,250 Rai).
The landscape is high steep mountains, the average steep is 80 degree. The highest point from sea level equals 1,267 meters whereas the average equal 800 meters. Covering with evergreen forest and mixed deciduous forests and overlapping high steep cliffs that are the sources of many streams e.g. Mae Koeng, Mae Jork, Mae Sin and Mae Pak. Since mountain is sandstone, it makes the soil decayed from the mountain become sandy soil with fine ventilation. The plain area nearby the slopes of the hill is good condition laterite soil.
Dong Ta Kien
In a sidewalk 15 Km from the headquarter is a dense bush of Ta Kien Tong ( Hopea odorata Roxb.) with 100 years of age. The biggest one is about 2 meters diameter.
Mae Jork Hot Spring
Located next to Mae Jork School, Mae Pak Sub-district, Wang Chin District, Prae Province. It is a hot spring coming up from the ground having a temperature of about 80°C. It looks strange and very beautiful, especially in the morning that covers with fog coming from steam right here.
Mae Koeng Luang and Mae Koeng Noi Waterfalls
Mae Koeng Luang and Mae Koeng Noi Waterfalls are beautiful cascading waterfalls composed of 5 stages like stairs, thus the local words “Mae Koeng” means stairs. These 2 waterfalls comes join together to Yom River at Ban Sob Koeng, Wang Chin District, Prae Province.
Mae Sin Waterfall
This is a small waterfall with rinsing water year round. You can walk through the side walk for 4 Km.
Pan Jen Waterfall
This small waterfall located upon Mae Koeng River as same as Mae Koeng Luang waterfall. 1 Km far from the headquarter, at the Ban Khang Jai School then turn right and go foe another 6 Km long.