Koh Surin Marine National Park is located 80km due west of Ranong Province along Thailand’s west coast. Together with nearby Richlieu Rock it is currently one of Thailand's two best snorkelling destination, due to shallow depths, generally clear visibility and an abundance of marine life, from the very small to the largest fish in the world, the mighty whale shark.

These fabulously colorful, teeming reefs start at depths of only 1.5 meters. The experience of this underwater ecosystem is therefore much more intense than at the nearby Similan islands, where the reef starts at a depth of 6 meters.

The Surin Marine Park showcases some 200 coral species, including fire corals, brain corals, mushroom corals, staghorn corals, multi-coloured soft corals and ruby-red gorgonian sea fans.

The coral is home to over 800 species of fish such as puffer fish, lion fish, butterfly fish, angel fish, moray eels, barracuda, sailfish, rock lobsters and a myriad of crustaceans.

The largest island is Koh Surin Nua which has an area of 19 sq. km and a highest point of 240m above sea level. To its immediate southwest lies the slightly smaller Koh Surin Tai; between the two is a strait only 200m wide, which can be crossed on foot during low waters.

There is basic accommodation available on the islands, but it is not worth making the round trip transfer unless you intend to stay the best part of a week. Most people snorkel the Surins on a day-trip from Khao Lak.