Koh Bon

Located 40 kilometres north-east of the Similans, and still within the Similan Islands National Marine Park territory, Koh Bon is a limestone (rather than granite) island, offering different scenery and two fantastic dive sites - West Ridge and Koh Bon Pinnacle.

West Ridge

At the northern end of Koh Bon Bay, West Ridge extends underwater from the western tip of the island, and offers one of the best chances in Thailand to see manta rays, particularly during January to May.

 Access to dive site:  By liveaboard
 Diver level:  Advanced
 Currents:  Mild, occasionally strong
 Depth:  10 – 40m

To the north of the ridge, at between 10 and 25m you’ll find coral bommies speckled across the slopes, and great patches of hard corals in the deeper areas. Triggerfish are common here, as well as lionfish, moray eels, sea snakes and unusually large schools of inquisitive batfish.

On the southern side, the bay slopes away to around 20m, and makes a great spot for night diving. Here you’ll find giant pufferfish, parrotfish and plenty of macro life amongst the hard corals and rubble, including mantis shrimps and lobster, octopus, cuttlefish and various nudibranchs.

The highlight of this dive site is the ridge itself whose topography and conditions attract the larger visitors. Strewn with colourful soft corals and whips, the ridge has spectacular vertical walls, and reaches a depth of 34m. Just be careful if the current is strong here, since down-surge can occur as the current hits the walls.

This part of the site is a cleaning station for manta rays, which come here to have their parasites removed by the cleaner wrasse; the rocks at 22 - 24m make a perfect vantage point from which to watch these graceful creatures swoop in. If you are unlucky however and miss the mantas, the critters along the walls, an occasional black-tip reef shark or leopard shark, and huge schools of fish, including trevally, yellowtail barracuda, sweetlips and snapper provide plenty of entertainment.

Koh Bon Pinnacle

Koh Bon Pinnacle is a small and exposed limestone pinnacle lying north-west of the island. The shallowest point is at 18m, and descending to 35 - 40m, its depth and potential for stronger currents makes this site suitable for experienced divers only.

 Access to dive site:   By liveaboard
 Diver level:   Advanced
 Currents:   Mild, occasionally strong
 Depth:   18 – 40m

Covered with yellow soft corals, anemones and magnificent gorgonians, the pinnacle is home to a good range of macro life, however this deep dive is really about the chance to see the bigger visitors. The resident napolean wrasse and big schools of trevally can often be spotted around the site, and keep a look out for black- and white-tip reef sharks, leopard sharks settled in the sand, eagle rays and manta rays.


Ocean Geo Diving & Tours

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Tambon Rawai,
Amphoe Muang
Phuket, 83130

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