Khao Yai is a mountainous area. It is the second largest National Park in Thailand, covers an area of 2,168 square kilometers, including evergreen forests and grasslands.
The park consists of complicated mountains such as Khao Rom, the highest about 1,351 meters above sea level. Moreover, the area has vastly grassy field alternating with productive forest. In the north and the east of the park is a mountain range which slopes down towards the south.
Another lies in the west of the park and together they capture such quantities of water to supply 5 important waterways leaving Khao Yai. This park lies largely in Nakhon Ratchasima Province, yet also includes parts of Saraburi, Prachinburi and Nakhon Nayok provinces.