Scuba Diving in Similan
The Ultimate Guide
The Similan Islands are an archipelago of nine granite islands in the Andaman Sea off Thailand’s west coast, protected as part of Mu Ko Similan National Park. Underwater you’ll find dramatic boulder formations, swim‑throughs, coral gardens and drop‑offs teeming with life. Manta rays and whale sharks cruise by at sites like Richelieu Rock and Koh Tachai, while reef sharks, leopard sharks, turtles and swarming schools of fusiliers and trevally are common. The park is only open from mid‑October to mid‑May, when calm seas and clear water make for world‑class liveaboard trips or speedboat day tours.
Difficulty
Moderate
Temperature
26–30°C
Visibility
20–40 m
Diving Highlights
Best Months to Dive
Getting to Similan for Diving
✈️Transportation
Fly into Phuket International Airport (HKT) or Bangkok’s Suvarnabhumi airport,
then travel north to Khao Lak on the mainland.
From Phuket it’s about a 90‑minute taxi or minibus ride to Thap Lamu pier, where most liveaboards boats depart.
Trips only available while the park is open.
Some operators also run transfers from Ranong or Krabi.
Country
Thailand
Currency
Thai Baht
Electricity
220V, 50Hz, plugs A/B/C
Cost of a Dive Trip in Similan
Liveaboard
Best Dive Sites in Similan
🐠Richelieu Rock
This lonely horseshoe‑shaped pinnacle lies north of the Similan Islands and is often called Thailand’s best dive. Its dense carpets of purple soft corals and sea fans harbour a kaleidoscope of macro life, while pelagic giants like whale sharks, manta rays, barracuda and trevally make surprise appearances. Currents can be strong and the site sits in open water, so it’s best suited to advanced divers.
🐢Koh Tachai Pinnacle
Located at the northern edge of the national park, this submerged dome rises from deep water and is swept by strong currents. It’s one of the best places in Thailand to see manta rays and occasional whale sharks, along with hunting barracuda, trevally and swirling batfish above the granite rocks.
🦈Koh Bon West
This limestone island features sheer walls draped in colourful soft corals. The western side is a manta ray cleaning station, so patient divers can watch these graceful giants circle over the reef while searching the cracks for moray eels, octopus and other macro life.
🐙Elephant Head Rock
A maze of granite boulders rising from deep water creates tunnels, swim‑throughs and hidden valleys. Reef sharks, groupers, batfish and lionfish patrol the passages, while currents add excitement. It’s an iconic site for experienced divers.
🐚West of Eden & Deep Six
These neighbouring sites on Island 7 showcase the Similans’ diversity. West of Eden’s boulders are carpeted with sea fans, anemones, feather stars and soft corals, giving way to the deeper walls and pinnacles of Deep Six. Look for rays, moray eels, turtles, dogtooth tuna and tiny critters like frogfish and nudibranchs.
🦑Shark Fin Reef & Boulder City
Off Island 3, massive granite outcrops and drop‑offs attract big pelagics. Currents can be brisk, bringing in mantas and whale sharks alongside huge schools of reef fish. Advanced certification is recommended to enjoy the thrilling drift dives here.
🐡Christmas Point
A cluster of boulders on Island 9 creates scenic swim‑throughs and tunnels covered in soft corals and sea fans. In the shallows are gardens of pore and staghorn corals, while bluefin trevally, sweetlips and groupers patrol the deeper passages.
What Divers Say About Diving in Similan
Marcus Rodriguez
DivemasterDiving the Similans feels like exploring an underwater playground. Enormous granite boulders are stacked into caverns and swim‑throughs, and currents sweep you past kaleidoscopic coral gardens. On a liveaboard trip we were buzzed by manta rays at Koh Bon and lost count of the turtles and leopard sharks at West of Eden. Richelieu Rock exploded with soft corals and macro life, and a whale shark even made a cameo. Between dives you sprawl on the sundeck eating Thai food and watching flying fish. The only downside is the crowds during peak season, but strict visitor limits keep it manageable. If you love big animals and epic scenery, the Similans deliver.
Frequently Asked Questions About Diving in Similan
When is the Similan National Park open?
The park opens mid‑October and closes mid‑May. Dive operators only run trips during this window, and permits are limited.
What marine life can I see in the Similans?
You can encounter manta rays, whale sharks, leopard sharks, reef sharks, turtles, barracuda, trevally, fusiliers and countless reef fish, plus macro critters like nudibranchs and harlequin shrimp.
Do I need to be an advanced diver?
Many sites have strong currents and deep swim‑throughs, so advanced certification and experience with drift diving are recommended. However, there are also sheltered sites suitable for confident beginners.
How many dive sites are in the Similans?
There are around 20 named sites across the nine islands, plus the nearby Surin Islands and Richelieu Rock. Liveaboards typically visit 10–15 sites during a trip.
Can I see whale sharks and manta rays?
Whale sharks and manta rays are seasonal visitors. December through April offers the highest chance of sightings at Koh Bon, Koh Tachai and Richelieu Rock.
Is a liveaboard better than a day trip?
Liveaboards provide access to more remote sites and sunrise or sunset dives, and they are often more cost‑effective if you plan multiple dives. Day trips are good for those short on time but cover fewer sites.