Similan Islands

The Similan Islands are an offshore archipelago in the Andaman Sea protected as a national marine park, renowned for clear waters, coral reefs and dive sites. The group contains 11 principal islands with steep granite formations, white-sand beaches and underwater pinnacles.

Popular activities include day-trip snorkelling, multi-day liveaboard diving and guided reef visits; notable islands host basic visitor facilities, viewpoints and mooring areas for dive boats. Marine biodiversity includes reef-building corals, reef fish, and seasonal sightings of larger species such as manta rays.

The islands were designated as a national park in the early 1980s to protect marine and island ecosystems, with park management enforcing seasonal closures and visitor limits. Facilities are minimal on most islands to reduce environmental impact.

The archipelago lies off the west coast of southern Thailand within Phang Nga province in the Andaman Sea and is reachable by boat from mainland piers and nearby island marinas when the park is open.

• Seasonal access: The archipelago comprises 11 main islands protected as a national park; visitor access is seasonal, typically open November through April due to monsoon conditions.
• Diving and snorkelling: Water clarity is often excellent with strong marine biodiversity, making the islands a top destination for scuba diving and snorkelling in the Andaman Sea.

What to See #

• Koh Similan (Main island): Koh Similan (Island 4) - the largest visitor island with white-sand beaches, viewpoints and base facilities for day trips and dive boats.
• Koh Bon and Koh Tachai: Koh Bon and Koh Tachai - satellite islands beyond the main cluster noted for steep drop-offs, pelagic marine life and high-quality dive sites.
• Key dive sites: Diving and snorkel sites such as Elephant Head Rock and Richelieu Rock lie near the park and attract international scuba divers for coral reefs and large pelagic species.