Pang Sida National Park is a part of Dong Phayayen-Khao Yai Forest World Heritage Site, covering the area of Ta Phraya District, Watthana Nakhon District, and Mueang District in Sakaew province. Most of the area of the park is high and complex mountain range, covered with tropical rain forest, dry evergreen forest, hill evergreen forest, mixed deciduous forest, and dry deciduous dipterocarp forest, which are the habitat of rare wildlife and more than 300 kinds of bird, such as elephant, wild ox, panther tigris, Siamese fireback, and peacock. There are more than 500 kinds of butterfly in the forest of Pang Sida National Park with more than hundred thousand in numbers. Therefore, it is acceptable from butterfly watchers in Thailand and is commended to be “Butterfly City of the Eastern Forest.” The common fascination of the butterfly at Pang Sida is that there are many kinds, including there is a source of freshwater crocodile that is believed to be the only source in Thailand.