It is located in the southeastern region of Thailand close to the border with Cambodia. The island runs parallel to the coast and appears very mountainous from the shore due to the mountain ridge which runs the length of the island.
The ridge is composed of several summits the tallest of which are: Khao Lan, Khao Chom Prasat, Khao Khlong Mayom, Khao Salak Phet and Khao Yai, which is the highest peak reaching 743m above seave leve.
The rock of the island is mainly Granitic and dates from approximately 230-195m years ago. The geology produces a very mountainous is land, but with rounded slopes rather than sheer cliffs.