Cheow Lan Lake or Rajjaprabha Dam Reservoir is in Khao Sok National Park in Suratthani Province, Thailand. It is an 185-square-kilometre (71 sq mi) artificial lake, inaugurated in 1987 with the construction of Rajjaprapha Dam by the Electricity Generating Authority of Thailand (EGAT) as a source of electricity.
The national park area is inhabited by a range of mammals such as tigers, elephants, tapirs and many monkey species. Birds such as hornbills, banded pittas, and great argus are as well forest residents. Less commonly seen reptiles include the king cobra, reticulated python, and flying lizards. The reservoir area includes the Khlong Saeng, Khlong Nakha and Kaeng Krung Wildlife Sanctuaries where rare animals can be found. West of Khao Sok National Park lies Sri Phang Nga National Park which extends the preservation area to 4,000 square kilometers.