Officially protected in 1980, Khao Sok National Park spans over 739 square km's in Thailand’s Surat Thani Province. This vast expanse of wilderness is made up of a maze of limestone karst formations, lush jungle rivers and dense rainforest, all resting on what was once the floor of an ancient ocean. The park is home to one of the oldest evergreen rainforests on Earth, estimated to be over 160 million years old, predating even the Amazon and Congo rainforests.