Khao Sok National Park (Thai: เขาสก, pronounced [kʰǎw sòk]) is in Surat Thani Province, Thailand. Its area is 461,712 rai ~ 739 square kilometres (285 sq mi), and it includes the 165 km² (64 sq mi) Cheow Lan Lake contained by the Ratchaprapha Dam. The park is the largest area of virgin forest in southern Thailand and is a remnant of rain forest which is older and more diverse than the Amazon rain forest.