Khao Sok National Park (Thai: เขาสก) is located in Surat Thani province in Thailand. Its land area is 739 km², and it includes the Chiao Lan reservoir dammed by the Ratchaprapha dam. The park comprises the largest area of virgin forest in Southern Thailand and is a remnant of rainforest which is older and more diverse than the Amazon Rainforest. The wild mammals include Malayan Tapir, Asian Elephant, Tiger, Sambar Deer, Bear, Guar, Banteng, Serow, Wild Boar, Pig Tailed Macaque, Langur, White handed Gibbon, Squirrel, Muntjak and Mouse Deer.
It is perhaps most famous for the Bua Phut (Rafflesia kerrii) flower which grows within the park. In addition to its flora, Khao Sok is inhabited by a wide variety of animals, including gibbons and barking deer.