Khao Sok National Park (Thai: เขาสก, pronounced [kʰǎw sòk]) is in Surat Thani Province, Thailand. Its area is 739 km2 (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.