Ko Bida Nok
Conditions & tides
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Marine forecast via Copernicus Marine. Score is a rule-based guide from swell/wind vs. the site's exposure — always dive your own assessment.
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About this site
Ko Bida Nok is a small island in the Phi Phi Archipelago, notable for its diverse underwater topography of steep walls, caves, crevices, overhangs, and coral gardens. The southern side of the island has a small underwater bay of reef slope and rocky floor beginning at 6–8 metres and ending on a sandy bottom at 20 metres. The west coast is lined with outcrops of various sizes that slope down to 26–30 metres, while the east coast is a reef slope mixing hard and soft corals with small outcrops. On the northern side, a narrow cave with its entrance at 20 metres has walls covered in soft corals and gorgonians, and the southwest side offers a vertical swim illuminated by surface light. Maximum depth reaches 30 metres.
The reef holds a solid range of marine life across the site. Leopard sharks and blacktip reef sharks are spotted along the reef line, while Kuhl's stingrays are common and small bamboo sharks hide in cracks. Schools of pickhandle barracuda patrol the blue beyond the reef edge. Along the reef itself, pufferfish, porcupine fish, and lionfish are regularly found, and macro hunters can search for ornate ghost pipefish, seahorses, and nudibranchs. Honeycomb morays, devil scorpionfish, clown anglerfish, and red fire gobies are also present, and anemones populate the higher ledges.
Conditions are intermediate in character, with visibility ranging from 10 to 25 metres and currents generally moderate. Water temperature stays between 27 and 30 °C. The site is diveable year-round, with the main season running November through April. Hazards include stonefish and venomous sea snakes, so careful buoyancy and awareness near the reef and sandy bottom are important.
Marine life here
Confirmed by our research team, reported by independent divers, or observed nearby via iNaturalist — each entry is labelled with its source.
Ghost pipefishGhost pipefishConfirmed present · 4 independent sources
PipefishPipefishReported here · unconfirmed
SeahorseSeahorseConfirmed present · 4 independent sources
SquidSquidConfirmed present · 2 independent sources
Moray eelMoray eelReported here · unconfirmed
CuttlefishCuttlefishReported here · unconfirmed
Sea turtleSea turtleReported here · unconfirmed
Reef sharkReef sharkReported here · unconfirmed
StingrayStingrayReported here · unconfirmed
Ornate ghost pipefishOrnate ghost pipefishConfirmed present · 3 independent sources
Manta rayManta rayReported here · unconfirmed
OctopusOctopusConfirmed present · 3 independent sources
Ocellaris AnemonefishAmphiprion ocellarisReported here · unconfirmed
Long-spined Crown-of-ThornsAcanthaster planciReported here · unconfirmed
Clark's AnemonefishAmphiprion clarkiiReported here · unconfirmed
Banded Sea UrchinEchinothrix calamarisReported here · unconfirmed
Blackspotted PufferArothron nigropunctatusReported here · unconfirmed
Magnificent Sea AnemoneRadianthus magnificaReported here · unconfirmed
Indo-Pacific Sergeant MajorAbudefduf vaigiensisReported here · unconfirmed
Swarthy ParrotfishScarus nigerReported here · unconfirmed
Moorish IdolZanclus cornutusReported here · unconfirmed
Leopard / zebra sharkLeopard / zebra sharkConfirmed present · 9 independent sources
BarracudaBarracudaConfirmed present · 6 independent sources
PufferfishPufferfishConfirmed present · 6 independent sources
TunaTunaConfirmed present · 2 independent sources
LionfishLionfishConfirmed present · 4 independent sources
SnapperSnapperConfirmed present · 4 independent sources
GrouperGrouperConfirmed present · 2 independent sources
NudibranchNudibranchConfirmed present · 7 independent sources
ScorpionfishScorpionfishConfirmed present · 3 independent sources
TrevallyTrevallyConfirmed present · 2 independent sources
ClownfishClownfishConfirmed present · 2 independent sources
Whale SharkRhincodon typusConfirmed present · 3 independent sources
FusilierFusilierReported here · unconfirmed
Harlequin ShrimpHymenocera pictaReported here · unconfirmed
WrasseWrasseReported here · unconfirmed
ParrotfishParrotfishReported here · unconfirmed
FrogfishFrogfishReported here · unconfirmed
MackerelMackerelReported here · unconfirmed
TriggerfishTriggerfishReported here · unconfirmed
AngelfishAngelfishReported here · unconfirmed
Durable tips from divers — access, hazards, marine life, facilities. For day-of conditions, use the report tool in the conditions card above.
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