Pickhandle Barracuda - Koh tachai Similan Islands Thailand

Koh Tachai

Koh Tachai – Pinnacle A.K.A. The Dome


Dive Tips

•    Max depth: 40+ meters 
•    Level of difficulty: Advanced open water upwards.  
•    Visibility: 10/40 meters
•    Current: Moderate to strong
•    Season: October through June



Although not part of the Similan Island Group, Koh Tachai is on every Thailand Liveaboard agenda, whether departing from Phuket or Khao Lak day trip or longer, Tachai is one of the best dive sites in the country.

Belonging more to the Surin Island group than the Similans, Tachai is definitely one on its own where scuba diving is concerned, it is my favourite dive site and maybe other instructors too.

There are a couple of diving sites around the island, yet there is only one Dome or Twin Peaks as it is sometimes known as. The sheer amount of life and size of fish here is breathtaking.

The site itself is series of huge granite boulders, there is very little coral to speak of, yet what it lacks in coral it sure makes up in fish life. There are usually two mooring lines one dropping down to twenty metres and the other at around fourteen metres. 

I recommend using these lines for both descent and ascent, and while we are on the subject, keep an eye on your depth and air gauges as time goes by very quickly here and it is easy to lose track of the important things.



During a Liveaboard adventure, divers do get to see some of the most beautiful islands that Thailand has to offer. I can assure you that there is no more beautiful island anywhere in the country than Koh Tachai.

To describe it with one word is impossible and would do the place an injustice. Koh Tachai conjures up all the superlatives one can say about an island this is the place you dream about being shipwrecked on, it is out of this world.

The beach is of the purest white finest sand that when it dribbles through your toes it actually tickles. The sea inside the bay of Tachai can only be described as azure cobalt blue. Some Liveaboard’s trips do actually take their guest’s ashore if you have the chance snap it up.

There are several dive sites around Tachai but there really is only one mega dive site, and possibly on its day the best dive site in the country. Yes, I know that is a bold statement especially when Richelieu Rock is only a few hours sailing away.

Believe me, when I say this, it does not have an equal when it comes to action, the reef itself is quite deep, the minimum depth being thirteen metres, maximum depth goes well beyond forty, and the site is made up of huge gigantic boulders.

The fish life can be almost overwhelming, and if you see the school of over one hundred Pick-handle Barracudas hunting then you will understand what I mean.

The current can be fast and due to the average depth here I recommended keeping an eye on your gauges for depth and air consumption.

Here is an excerpt from my personal logbook just so you know I am not making it:

At Koh Tachai Pinnacle today the viz is around 15 metres, which is a little below the normal -still decent though. The current was running quite quickly as it does here, this is good news as now we will get to witness the predators in action.

As we descended down to the depths of Tachai we were greeted by a team of batfish, they are very inquisitive fish and came very close to check us out.

The scene down there was frantic fish everywhere, yet we managed to find a quiet spot where we enjoyed a little tranquillity watching juvenile oriental sweet lips as it fluttered around the bottom is a lovely site.

Then suddenly a large school of Big Eyed Trevallies came hurtling into view, amongst them was an even bigger school of two stripped Fusiliers… the sheer amount of fish on the dive was ridiculous.

We were all settling into the dive, the current picked up a little bit, nothing that we could not handle, then out of know where one appeared, as they normally do, then another then several. Before we knew it we were completely surrounded by the large Pickhandle Barracudas that run this place, they are top predator here; very curious as to why we were in their area, of course, we had no answer.

Who would blink first, obviously we did there was now over a hundred of these metre and half fish with a toothy grin to send shivers down the most experienced diver's wetsuit. 


They formed a tight packed, they had gone into attack mode, comfortable we were no threat, they started to dart off, one by one, into the reef below picking off poor unsuspecting fish; the hapless baitfish never saw them coming. 

The speed at which these magnificent fish power towards their prey is incredible, swimming into the current the barracudas hunting is an amazing site to witness.

We watched them for quite a while, and as our air was running low it was time to think about ascending to shallower depths, as we made our way to the mooring line to do the safety stop, an almost two metres barracuda came by on his own and within touching distance and flexing his jaw, revealing for one last time the huge array of teeth they have then he twitched his tail and was gone. 

Extraordinary dive on one of the best sites in the country, Koh Tachai is outstanding and if you ever get chance to dive it only then will you appreciate the sheer volume of fish and the outlandish menace the barracudas hold over the reef. Superb

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