The Koh Surin archipelago is a 135 square kilometres area lying in the Andaman Sea some 53 kilometres off mainland Ranong Province. The park's five islands lie just south of the border with Burma. The two main islands, Koh Surin Nua and Koh Surin Tai, are separated by a narrow strait, only 200 metres wide, with almost no flat ground beyond small pockets of mangrove and little beaches which nestle in the many coves. The 2 islands cover 19 square kilometres respectively 12 square kilometres with the highest point on the latter one elevating to 350 metres. The other islands in the group are only rocky islets, sparsely covered with scrub vegetation. Koh Surin was uninhabited till about the time of World War II. Even after it was declared a national park, in 1981 there were only a few hundred people to relocate. Today, park officals have a station on Koh Surin Nua, while Koh Surin Tai is home to a tiny Chao Le fishing community. In the 1960's, was a certain amount of logging, especially on the western side of Koh Surin Nua, where gum and ironwood trees were selectively cut. But the difficult terrain, as well as the problem Koh Surin of transporting the logs by sea, doomed the enterprise.
Until recently, Koh Surin's reefs were subject to much blasting by fishermen. Sport diving, gamefishing and simple nature excursions are now the main attractions. Even though some of the coral reefs around Koh Surin to all appearances remain spectacularly healthy. Tourism Authorities have installed mooring buoys on some reefs and these have proven effective in reducing anchor damage to corals. Again, as in other areas of the Andaman Sea and the Gulf of Thailand, commercial collecting is pushing some species of shellfish to the brink of local extinction.