Koh Tachai is an Andaman Sea island within Similan National Marine Park, open to divers from mid-October to mid-May. The seven sites in this area range from shallow beginner-friendly reefs to deep walls and pinnacles descending beyond forty metres, suited to advanced divers comfortable with strong currents and potential down currents. Sites such as Koh Bon Pinnacle and Hin Luang demand drift diving experience, while Turtle Rock and The Aquarium offer more accessible conditions. Recorded species include whale sharks, whitetip reef sharks, blacktip reef sharks, marble rays, napoleon wrasse, green sea turtles, and giant moray eels. All sites require boat access.
Monthly water temperature across Koh Tachai's sites, from satellite sea-surface data corrected for depth. The band shows the site-to-site spread.
The park season runs from mid-October to mid-May, concentrating all diving into the dry-season window. Water temperatures are warm and fairly stable throughout this period, with the warmest conditions typically in late spring near the end of the season.
2 operators
Water temperature around Koh Tachai ranges from about 28°C in November to 30°C in April, based on satellite sea-temperature data for its dive sites.
With water around 28–30°C, a rash guard or 3mm shorty works in Koh Tachai year-round.
Fin maps 7 sites in Koh Tachai (7 scuba diving sites and 3 snorkelling spots, with some suited to both).
4 more sites to explore
