Koh Bon / Tachai

Koh Bon & Koh Tachai

2 Dives / Lunch on MV Koon 9 - Full Day

5,400 THB / PERSON

Pay extra for national park entrance fee 300 THB for Thai people / 700 THB for Foreigner
Pay extra for Equipment rental full set 500 THB
Dive computer 300 THB/Day

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** This Trip Is For Certified / Licensed Divers Only **

If you are not a certified/licensed diver please go to this link

Koh Bon / Tachai

Koh Bon Ridge

Koh Bon Ridge is the dive site that stretches around the cape on the western corner of Koh Bon Island, which is not part of the Similan Archipelago although part of the same National Park administration. The stepping rocky ridge that can be seen out of the water continues all the way underwater, giving the name to the dive site. The underwater scenery at Koh Bon Ridge is absolutely unique, with an incredible amount and diversity of marine life. Koh Bon is also the hot spot for Mantas in Thailand! We usually start our dive near the bay at the south side of the ridge. Here the scenery is characterized by a straight wall that at 10-12 meters of depth changes into a sloping hard coral garden, the corals here are in pristine conditions. The area is teeming with thousands of reef fish including species that are not commonly found in other Thailand dive sites. Keep an eye towards the deep side as White Tips and Guitar Sharks are sometimes spotted there. We then move to the ridge, where the scenery changes drastically with large square rocks that get deeper and deeper, like giant steps. The rocks on Koh Bon Ridge are covered by small soft corals of different colors, offering a stunning visual impact. This part of the dive site is often subject to strong current, which on the plus side attracts lots of fairly sized pelagics like Trevally and Tunas. The ridge is also the spot where the oceanic Manta Rays tend to gather, as the whole area is a large cleaning station…keep an eye to the blue all the time! The ridge steps end at around 35 meters of depth, and at the bottom of it lies a “hidden gem” that not many divers know about, a glowing orange anemone (see photo). It is usually possible to get to the end of the Koh Bon Ridge only when the current is not too strong. We then go around to the north side of the ridge and proceed in that direction, here the bottom changes again into a sloping hard coral garden and small rocks. Keep an eye to the rocks as here is often possible to spot octopus (if not too camouflaged!) and Banded Sea Kraits

Koh Tachai Pinnacle

Koh Tachai Pinnacle

Koh Tachai Pinnacle, on a good day, may very well compete with Richelieu Rock for the title of best Thailand dive site. This group of submerged boulders is, on most days, crossed by very particular (often strong) currents that attract an incredible amount of predatory fish in schools. With a bit of luck, especially between January and May, Mantas and Whalesharks can also be encountered here! Koh Tachai Pinnacle is made by a submerged group of gigantic granite boulders that remind of the Similan Islands dive sites. The summit is at around 10 meters of depth and has a mooring line/buoy to assist divers in their descent. There are actually two pinnacles, the main pinnacle in the south is bigger and is the area where most dives at Koh Tachai Pinnacle take place. It is made by a huge dome-shape boulder surrounded by many other smaller ones. The scenery on the pinnacle is very diverse, as the southern side is characterized by large and oddly shaped boulders that create a stunning underwater scenery, while on the north side lays one of the most beautiful and pristine coral gardens in Thailand. This huge pinnacle connects to the smaller second pinnacle to the north through a sand patch at 24 meters, with an approximately 50 meters long swim. The top of the northern pinnacle lies at 18 meters of depth, and comprises a wide range of rock formations and is home to large and beautiful sea fans and soft corals in pristine conditions. But the amazing underwater topography and coral reef pale in comparison to the insane amount of fish and marine life that can be found at Koh Tachai Pinnacle. Large schools of huge Giant Trevally, Bluefin Trevally, Dogtooth Tunas and Rainbow runners are often hunting around the boulders offering a spectacular show for the divers. A massive school of Chevron Barracudas is occasionally found whirlpooling over the pinnacles. Large Marble Groupers literally all over the place,  and schools of curious Batfish often keep us company during the safety stop. And these are just the major highlights, but there is much much more to be spotted here, including occasional passage of Manta Rays and Whalesharks when lucky! One dive is simply not enough to fully enjoy this amazing dive site. More often than not, the current at Koh Tachai Pinnacle can be very strong and that’s why the dive site is teeming with so much life. This can make it a challenging dive, although it can be easily managed by hiding behind the boulders and swimming close to the bottom.


Diving insurance
Free transfer around Khaolak, Namkhem charge 500 THB/Pax
Extend Night 5000THB / Day
Nitrox 300THB / Tank, Divers 19 dives up free Nitrox 1tank/pax/day, Divelead free Nitrox 1tank/pax/day
15L air tank for rent 300THB/day
Price included Vat


Park fee
Equipment Rental
Free transfer around Khaolak, Namkhem (Phuket, Out of Khaolak, Namkhem charge 500THB/Pax)
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MV Koon 9 - Weekly Plan Day Trip

10:30 First Dive/ 14:00 Second Dive 

Dive 1
Dive 2
SundayRichelieu RockRichelieu Rock
MondaySurin IslandsSurin Islands
TuesdaySurin IslandsSurin Islands
WednesdayTachai PinnacleKoh Bon
ThursdaySimilan Island no.5-6Similan Island no.7
FridaySimilan Island no. 9Similan Island no. 9
SaturdayKoh BonTachai Pinnacle
Boat Schedule - Richelieu Rock
SundayNot Available-
MondaySimilan Islands ( Lunch on the Similan Island No.4 )2 Dives
TuesdayNot Available-
WednesdayNot Available-
ThursdayNot Available-
FridaySimilan Islands ( Lunch on the Similan Island No.4 )2 Dives
SaturdayNot Available-



06.30 - 7:30

Pickup from hotels


The Seastar team welcomes you on board at Seastar Pier (Tub-lamu Pier) to check in. Serve you with hot drinks and a bakery.


Depart to MV Koon 9 by speedboat.


Arrive at our spacious boat, MV Koon 9. Dive No. 1 at Koh Bon or Koh Tachai (diving time: 50 minutes)


Enjoy a great lunch on MV Koon 9 and a relaxing time.


Dive No. 2 at Koh Bon or Koh Tachai (dive time: 50 minutes)


Depart from MV Koon 9 by speedboat


Arrive at Seastar Pier (Tub-lamu Pier).and transfer back to your hotel.

More Information

Phone: +6684-156-9514


Booking Day Trip: [email protected]
Booking Liveaboard: [email protected]




Pick up from hotels or meet at Sea Sky Travel Pier


Departure from Sea Sky Travel Pier by speed boat


Arrive at the dive site


First dive (Diving time 50 minutes)


Lunch Buffet at Surin Island and relaxing time


Leaving the Island


Second dive (Diving time 50 minutes)


Depart from Dive site


Arrive at the Sea Sky Travel Pier and transfer back to hotel