Declared a national park in 1980, Khao Sok in southern Thailand’s Surat Thani Province is a primeval wilderness frozen in time. Towering limestone karsts and winding rivers carve through a sprawling rainforest so ancient it once lay beneath a prehistoric ocean. At 160 million years old, Khao Sok’s evergreen rainforest offers travellers a rare glimpse into a world that has survived ice ages, shifting continents and humanity’s relentless march.