Mu Ko Surin National Park is a remote continental archipelago in the northern Andaman Sea, 55 km off Thailand's coast near the Myanmar border, prized for healthy hard-coral gardens, granite-boulder pinnacles, and a Moken sea-gypsy community. Reached only by liveaboard or speedboat day trip from Khao Lak and Kuraburi, it is open roughly mid-October to mid-May and closed for the southwest monsoon.
Destination info
Conditions, highlights, and the resident marine life.
Conditions
Water and air temperature across the year.
WaterAirDryShoulderWet
Description
The Surin Islands form a five-island continental archipelago in the northern Andaman Sea, about 55 km offshore in Phang Nga province and only ~18 km from the maritime border with Myanmar. Gazetted as Thailand's 30th national park on 9 July 1981, the park covers roughly 135 km², of which about three-quarters is sea. The two main islands, Ko Surin Nuea and Ko Surin Tai, are separated by a shallow channel and ringed by some of the most extensive, healthy fringing hard-coral reefs in Thailand, complemented by submerged granite-boulder pinnacles offshore. Surveys have recorded over 260 reef-fish species, 68 corals, 48 nudibranchs and 31 shrimps. The water is warm year-round (roughly 28–30°C) and visibility is variable, often 15–30 m, dropping when plankton blooms—the same blooms that draw whale sharks and manta rays, most likely February through April. The indigenous Moken ('sea gypsies'), numbering a few hundred, live at a village on Ko Surin Tai and hold deep traditional knowledge of these waters. The park is open only mid-October to mid-May; the southwest monsoon forces a full closure from mid-May to mid-October, which also gives the reefs recovery time. Famed Richelieu Rock lies a short distance away and is catalogued separately.
Highlights
What makes this dive worth the trip.
Mu Ko Surin National Park is open only from mid-October to mid-May (officially 15 October–15 May); the park closes completely for the southwest monsoon from mid-May to mid-October, when strong winds and heavy rain make the crossing unsafe and the closure gives the reefs and marine life recovery time.
The Surin reefs rank among the healthiest and most extensive shallow hard-coral systems in Thailand, with documented diversity of over 260 reef-fish species, 68 corals, 48 nudibranchs and 31 shrimps—though the park suffered severe bleaching in 1998 and again in 2010 (the Reverse Indian Ocean Dipole event killed an estimated ~90% of coral at some sites), with authorities reporting near-full recovery by 2019.
Whale sharks and manta rays are possible at Surin, with the best odds during the February–April window when increased currents and plankton draw larger pelagics; encounters are never guaranteed and the Surin sites are better known for prolific reef life than reliable big animals.
Marine life
40 species you’re likely to encounter on a dive here.
Dive sites
6 signature sites at this destination.
Torinla Pinnacle
A sprawling granite pinnacle on a sandy bottom east of Ko Torinla, usually dived first thing in the morning and attached to a permanent mooring buoy. The summit hosts a resident herd of around 15 humphead (bumphead) parrotfish—rarely seen in such numbers elsewhere—along with paired Napoleon wrasse, schools of bigeye snapper, goatfish and butterflyfish. Deeper sandy areas shelter Kuhl's stingrays and whitetip reef sharks, while the rocky structure is excellent for macro life including Flabellina and Risbecia nudibranchs and blennies. Currents are generally mild but can strengthen on full and new moons.
7–30 mintermediateLiveaboardModerateVisibility 15–30 m
Koh Torinla (Ko Khai)
A long fringing hard-coral reef—mainly staghorn with massive Porites bommies that break the surface at low tide—running north to south off the east coast of Ko Torinla. Liveaboards and day boats moor along its length and divers make a relaxed drift from one end to the other in usually excellent visibility and weak current, making it one of the most beginner-friendly dives in the park. Fish life is prolific: cardinalfish, humpnose bigeye bream, twin-spot and five-lined snapper, batfish, pickhandle barracuda and Spanish mackerel, with grey and whitetip reef sharks, eagle rays and shovelnose rays also recorded.
5–30 mbeginnerLiveaboardLightVisibility 15–30 m
South East Point (Ko Surin Tai)
Two parallel jumbles of granite boulders at the southeast point of Ko Surin Tai that run perpendicular into deeper water, with a rubble floor between them. A favourite macro and night-dive site: harlequin and robust ghost pipefish shelter on the soft corals and sea fans, while cowries, ribbon eels and mantis shrimp inhabit the rubble and crevices, alongside Andaman rabbitfish, Indian sailfin tang and Andaman sweetlips. Currents can be strong on the exposed flanks but the boulders offer shelter.
5–25 mintermediateLiveaboardModerateVisibility 10–25 m
Ao Mai Ngam (HQ Channel)
The shallow, sheltered fringing reef in Mai Ngam Bay on the west side of Ko Surin Nuea, near the park headquarters area and reachable directly from the beach. The reef edge sits 200–500 m offshore in calm, shallow water with vibrant hard corals and small reef fish, making it the park's premier easy snorkel and check-/training-dive site for beginners and children. Calm conditions and clear water on good days, with little current.
2–12 mbeginnerDay boatLightVisibility 8–20 m
Hin Kong
A pile of giant granite boulders ('Hin Kong' translates as 'a pile of rocks') stacking from above the surface and sloping down to a sandy bottom near the main islands. The site holds large numbers of redtooth triggerfish, whip corals spreading across the floor, and is a reliable place to find lobsters in the crevices; occasional sightings of larger sharks cruising the area have been reported. A good intermediate boulder dive with variable current.
5–22 mintermediateLiveaboardModerateVisibility 10–25 m
Koh Chi
The northernmost and smallest island of the group, with gentle slopes and granite boulders on its western side dropping to around 22 m. Known for more frequent pelagic action than the sheltered reef sites: turtles, trevally, barracuda, tuna and reef sharks, with blacktip reef sharks seen more often here than in the Similans. Currents can be strong, so the site is better suited to divers comfortable with some drift.
5–22 mintermediateLiveaboardModerateVisibility 15–30 m
Where to dive & stay
Local dive centers, resorts, and hotels.
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