Part of the park, but geologically and physically quite separate are Koh Bon and Koh Tachai.
Ko Bon (Bon Island) – with no beach and no accommodation this is still an island to visit. A portion of the islands coral was destroyed by dynamite fishing before it became part of the National Park. It still holds some stunning scenery. This is also the most common site for sightings of Manta Rays.
Ko Tachai (Tachai Island) Tachai Island is located at the northern most tip of the park. There is a beautiful white powdered beach on the island. There are several sites suitable for SCUBA diving. In addition there are several reefs suitable for snorkeling. Whale sharks and Manta rays are often found here during their seasons. Facilities incloud a freshwater source, campsites, a restaurant and small boats for snorkeling.
”Similan” comes from the Sea Gypsies. They speak a language similar to Malay. They named them “The Nine Islands” (Sembilan is “nine” in Malay). They designate the islands by names in Thai-and a number. The islands achieved national park status in 1981 and thus are fully protected under Thai law.