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 exotic flora, Khao Sok is inhabited by a wide variety of animals, including gibbons and barking deer.
The 94 m high Ratchaprapha dam was built in 1982 at the Khlong Saeng River, a tributary of the Phum Duang River.