The park is an archipelago consisting of 11 islands, occupying an area of approximately 140 km2 with a land area of about 26 km2.[2] For convenience, the Thai Department of National Parks (DNP) has assigned numbers to the islands. From north to south, they are:[3]
Island 11: Ko Tachai
Island 10: Ko Bon, AKA Ko Talu
Island 9: Ko Ba-ngu, AKA Ko Bayu
Island 8: Ko Similan
Island 7: Ko Hin Pousar
Island 6: Ko Payu, AKA Ko Pa Yu
Island 5: Ko Ha
Island 4: Ko Miang, AKA Ko Meang. Park HQ is here.
Island 3: Ko Payan, AKA Ko Pa Yan
Island 2: Ko Payang, AKA Ko Pa Yang
Island 1: Ko Huyong, AKA Ko Hu Yong
The Similans lie 70 kilometres off the coast of Phang Nga Province. "Similan" is a Yawi word meaning "nine". Ko Bon and Tachai were added to the national park in 1998.