Similan Islands
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Why dive in Similan Islands?
BEST SEASON
Featured Animals 10
- Unlikely
- Likely
- Very likely
Variable Frequent sightingsGiant Oceanic Manta Ray
Mobula birostris
The Giant Oceanic Manta Ray is the world's largest ray, with a disc width that can reach up to 9 meters. It is a circumglobal species found in tropical to temperate pelagic waters, often near coastlines, reefs, and in the open ocean, diving to depths of 1,000 meters. These filter feeders primarily consume zooplankton, including mesopelagic sources, and can also eat small fish. While generally solitary, they aggregate at feeding grounds and cleaning stations. The species is currently listed as Endangered due to overfishing and low reproductive rates.
BEST SEASON
Variable Frequent sightingsGiant Trevally
Caranx ignobilis
The giant trevally (Caranx ignobilis) is a large, powerful predatory fish found throughout the tropical Indo-Pacific region. Known for its steep head profile and robust body, it can reach up to 170 cm in length and 80 kg in weight. This apex predator feeds primarily on fish, but also consumes crustaceans and cephalopods, often hunting in solitary or small groups, though juveniles form schools.
BEST SEASON
Variable Frequent sightingsGrey Reef Shark
Carcharhinus amblyrhynchos
The Grey Reef Shark (Carcharhinus amblyrhynchos) is a medium to large-sized requiem shark, common in Indo-Pacific coral reefs and adjacent waters. Characterized by its grey body and a distinctive broad black band on the trailing edge of its caudal fin, it is a fast and agile predator. These sharks are known for their social daytime aggregations, which disperse at night for individual hunting.
BEST SEASON
Diurnal Frequent sightingsHumphead Wrasse
Cheilinus undulatus
The Humphead Wrasse is one of the largest reef fish, identifiable by a prominent hump on its forehead and thick fleshy lips. It is a protogynous hermaphrodite, meaning individuals are born female and some transition to males later in life. This carnivorous species plays a crucial role in coral reef ecosystems by preying on hard-shelled invertebrates and toxic animals like the crown-of-thorns starfish.
BEST SEASON
Diurnal Frequent sightingsOcellated Eagle Ray
Aetobatus ocellatus
The Ocellated Eagle Ray, also known as the Whitespotted Eagle Ray, is a large ray characterized by a dark greenish-grey to black dorsal surface covered with numerous white spots, and a white underside. It possesses a flattened, diamond-shaped body, a prominent snout, and a long, whip-like tail armed with venomous spines. This species primarily feeds on hard-shelled invertebrates, such as mollusks and crustaceans, which it crushes with its specialized dental plates.
BEST SEASON
Diurnal Frequent sightingsPickhandle Barracuda
Sphyraena jello
The Pickhandle Barracuda is characterized by its elongated body, prominent jaw, and distinctive dark bars on its back. It inhabits warm coastal waters and is known to be a top predator, primarily feeding on smaller fish.
BEST SEASON
Variable Frequent sightingsReef Manta Ray
Mobula alfredi
The Reef Manta Ray (Mobula alfredi) is a large filter-feeding ray found in tropical and subtropical waters, primarily around coral reefs and coastal areas. Known for its pelagic lifestyle, it feeds on zooplankton and exhibits complex social behaviors, often forming aggregations at feeding or cleaning stations. This species is listed as Vulnerable due to threats from overfishing and its slow reproductive rate.
BEST SEASON
Diurnal Frequent sightingsTitan Triggerfish
Balistoides viridescens
The Titan Triggerfish (Balistoides viridescens) is the largest species of triggerfish, reaching up to 75 cm in length, with a distinctive greyish-green body and a "moustache" pattern around its mouth. It is known for its powerful jaws and teeth, which it uses to crush the shells of sea urchins, crabs, molluscs, and coral. This diurnal fish is highly territorial, especially when guarding its nest, and can exhibit aggressive behavior towards intruders, including divers.
BEST SEASON
Diurnal Frequent sightingsWhale Shark
Rhincodon typus
The whale shark is the largest fish in the world and a gentle filter feeder.
BEST SEASON
Nocturnal Frequent sightingsWhitetip Reef Shark
Triaenodon obesus
The Whitetip Reef Shark is a slender, medium-sized shark easily identified by the distinctive white tips on its dorsal and upper caudal fins. Primarily nocturnal, it spends its days resting in caves and under ledges on coral reefs and hunts at night for bony fishes, crustaceans, and cephalopods. These sharks are generally social, often found in groups during the day, but can hunt individually or cooperatively.
BEST SEASON
More marine life 66
Bigeye TrevallyCaranx sexfasciatus
Black DurgonMelichthys niger
Blacktip Reef SharkCarcharhinus melanopterus
Blue-Ringed OctopusHapalochlaena spp.
Blue-barred ParrotfishScarus ghobban
Bluecheek ButterflyfishChaetodon semilarvatus
Bluering AngelfishPomacanthus annularis
Bluespotted CornetfishFistularia commersonii
Bluespotted Ribbontail RayTaeniura lymma
Bluestreak Cleaner WrasseLabroides dimidiatus
Blunt-head ParrotfishChlorurus microrhinos
Brownbanded Bamboo SharkChiloscyllium punctatum
Bullethead ParrotfishChlorurus sordidus
Bumphead ParrotfishBolbometopon muricatum
Clown TriggerfishBalistoides conspicillum
Coconut OctopusAmphioctopus marginatus
Coral HindCephalopholis miniata
Dogtooth TunaGymnosarda unicolor
Ember ParrotfishScarus rubroviolaceus
Emperor AngelfishPomacanthus imperator
Garden EelHeterocongrinae
Giant MorayGymnothorax javanicus
Giant clamTridacna gigas
Glider FlyingfishCheilopogon atrisignis
Golden SpadefishPlatax boersii
Great BarracudaSphyraena barracuda
Green Sea TurtleChelonia mydas
Guineafowl PufferArothron meleagris
Harlequin ShrimpHymenocera picta
Hawksbill Sea TurtleEretmochelys imbricata
Jenkins' WhiprayPateobatis jenkinsii
Latticed ButterflyfishChaetodon rafflesii
Leaf ScorpionfishTaenianotus triacanthus
Mimic OctopusThaumoctopus mimicus
Oceanic Whitetip SharkCarcharhinus longimanus
Orange-lined TriggerfishBalistapus undulatus
Orbicular BatfishPlatax orbicularis
Oriental SweetlipsPlectorhinchus vittatus
Ornate Ghost PipefishSolenostomus paradoxus
Painted FrogfishAntennarius pictus
Palette SurgeonfishParacanthurus hepatus
Peacock Mantis ShrimpOdontodactylus scyllarus
Pennant CoralfishHeniochus acuminatus
Potato GrouperEpinephelus tukula
Rainbow RunnerElagatis bipinnulata
Redtooth TriggerfishOdonus niger
Regal AngelfishPygoplites diacanthus
Ribbon EelRhinomuraena quaesita
Silky SharkCarcharhinus falciformis
Silver SweeperPempheris schwenkii
Silvertip SharkCarcharhinus albimarginatus
Spanish DancerHexabranchus sanguineus
Spot-fin PorcupinefishDiodon hystrix
Spotted Eagle RayAetobatus narinari
Spotted SeahorseHippocampus kuda
Stellate PufferArothron stellatus
StonefishSynanceia verrucosa
Tawny Nurse SharkNebrius ferrugineus
Teira BatfishPlatax teira
Threadfin ButterflyfishChaetodon auriga
Tiger SharkGaleocerdo cuvier
Yellow BoxfishOstracion cubicus
Yellow Longnose ButterflyfishForcipiger flavissimus
Yellow-lipped Sea KraitLaticauda colubrina
Yellowfin TunaThunnus albacares
Zebra SharkStegostoma tigrinum
Where is Similan Islands
Andaman Sea · Thailand
Frequently asked questions about Similan Islands
When is the best time to dive in Similan Islands?
The best time to dive in Similan Islands is from December to April. In those months the water is between 26°C and 32°C.
What marine life can you see diving in Similan Islands?
Divers can encounter 76 species in Similan Islands. Highlights include Giant Oceanic Manta Ray, Giant Trevally, Grey Reef Shark, Humphead Wrasse, Ocellated Eagle Ray, and Pickhandle Barracuda.
When can you see the Giant Oceanic Manta Ray in Similan Islands?
The Giant Oceanic Manta Ray is most often seen in Similan Islands from April to September.
When can you see the Ocellated Eagle Ray in Similan Islands?
The Ocellated Eagle Ray is most often seen in Similan Islands from March to October.
When can you see the Reef Manta Ray in Similan Islands?
The Reef Manta Ray is most often seen in Similan Islands from March to September.
What is the water temperature in Similan Islands?
Water temperature in Similan Islands ranges from 26°C in December to 32°C in April.
What wetsuit do I need to dive in Similan Islands?
Most divers wear a 3 mm wetsuit in December, when the water drops to 26°C, and a rash guard or a 1–3 mm shorty in April, when it reaches 32°C.
What is the visibility like when diving in Similan Islands?
Visibility in Similan Islands ranges from 0 m to 40 m. The water is clearest from January to April.
What are the currents like in Similan Islands?
Divers in Similan Islands can expect light, moderate, strong, or very strong currents, depending on the month and the dive site.
What can you see on a night dive in Similan Islands?
After dark, Similan Islands reveals nocturnal species such as Whitetip Reef Shark, Bluespotted Ribbontail Ray, Brownbanded Bamboo Shark, Giant Moray, Leaf Scorpionfish, and Oriental Sweetlips.
Where is Similan Islands located?
Similan Islands is a dive destination in Thailand, in the Andaman Sea.
Every answer is built from the conditions and sightings data we keep for Similan Islands. Spotted something that looks off?
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