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  • Mikko Paasi

The First mine dive ever done in Thailand

I’ve always been passioned about mine diving, actually I started my professional dive carreer in Ojamo mine 1998 where I went through a year long instructor training and during that year we conducted nearly 300 dives in the mine. Back in the 90’s there was no proper training available so we pocked our heads around the first chambers with our c battery loaded 100 lumen bulb lights.



Bottomline Projects Foundation’s team diver Cedric Chan tying off to a stone in one of the massive tunnels in the mine. These stones were rare and you can see how easily the rock flakes away, making tying off even harder.

Today, with all the developing technology in diving industry, overhead environment diving has developed to a totally new level. DPV’s, rebreathers and powerfull hand held torches help us penetrate futher than we could have even dreamed of few of decades ago.

Even if mine diving might be popular in Europe, in Thailand it is a totally new priviledge and according to my knowledge it was never done here before we decided to start scouting flooded old abandoned mine sites couple years back.



Like any other exploration project, this one started a long time a go on a drawing board with a pint of beer but after a long period of scouting around we finally started to get serious options of mines that might be worth to check out.

This is a story of the first two flooded mines discovered and dived in Thailand.


Thailand has a rich mining culture that dates back a few hundred years. The main minerals have been lead, tin, zink, gold and other heavy metals. Our first exploration target, the Sahakorn Nikon mines is located in Kanchanaburi province near the Mayanmar border, north-west of Thailand. Some say it is the biggest mine complex in the whole of Asia. For three generations and about a hundred years the Bhol family has extracted lead minerals from under the stone mountain the local call the “Everest of Thailand” for the shape of it. The minig stopped here over 30 years ago and the underground section has been submersed ever since. This was pretty much all the information we could find from the mine.



We are based on a small island, in the middle of the Gulf of Thailand, called Koh Tao, where I have been running my dive center for past 25years. Koh Tao Divers is where we train our team and other likeminded divers. Our first dive team consists of two full cave and Kiss Sidewinder mccr divers Naomi Allen and Pasi Laihanen, a couple who both work as instructors at KTD, and ofcourse my self as the expedition leader.


To get to the mine area we first needed to load up all our gear to a high speed catamaran that took us to mainland where we had a minivan waiting to take us on the second leg of the journey, a 800 kilometer drive up north. On the way we picked up two dry cavers David Templeman and Karn Romyasai who had been in these mines before and knew the coordinates and the location of the possible diving spots inside the mines.

We arrived on the site around 04:00 am in the heart of the night. This area is infamous about it’s heard of wild elephants that kill tens of local every year. Cutting away the jungle with our machettes in the dark pushing our way toward the hidden entrance, we made our selves very vounerable to the wild life surrounding us.



Eventually we found the entrance and started to descend down a spiralling drive way that lead us to the water level after a half a kilometer of dragging our equipment through the slippery down hill. Once down at the water level we realised that this mine is a monster, in both, the size and the hostile condition it was in. Quick sand that sucked you in down to your hips if you werent carefull, mud and rusty fragile structures all over. We couldn’t help imagin how it will be under the surface..


Encouraged by the fact that we had come all the way here and that we were actually about to do the first mine dive in the Kingdom, we started our way toward the shaft that lead down to who knows where. My tool for the job was a mechanical ccr, Kiss Sidewinder with 2 s40 cuf’s bailouts sidemounted on both sides, my collegues, Pasi and Naomi, were both on open circuit sidemount. While gearing up, I had torn my dry suit wrist seal completely off and since I didn’t have spare with me, I had zip-tied my right sleeve to minimize the leak. Lucky the water was 20 dergees celcius.





These mines do not have maps or blue prints so that we could have had even a slightiest idea whats down there waiting for us. By the time I got my reel line attached to the super structure the visibility at the shaft had dropped from 5 meters to zero. Regardless we started our dive dropping down and feeling our way in until we reached the first tunnel at just 10 meters depth. Everything was covered with a thick layer of the finest dust imaginable and we were lucky to manage to do a few tie offs on the way until we popped to another vertical shaft with massive amount of plumbing and rusty ladders going all directions. We had just traversed to another vent shaft that led straight away to the ground surface and exited the mine about 50 meters above us. Unfortunately when you calculate the risk versus reward, this experience was not worth to risk any more exploring with the given equipment and gasses we had with us. Yet again, we think the shafts will keep going and given the amount of structure there was, it must go for quite some way.



At the sunrise we surfaced back to the ground level and out from the darkness of this monster of a mine. Next site was about two hour drive away. Time for some breakfast and get our focus on the next dive in another abandoned flooded mine.


11:00am. This time the approach was a bit easier since we had the day light with us. Once we found the entrance we started walking in following David, who was leading us to the spot where the tunnel submersed. We had our hopes realistic because we had just dove a massive and fairly potential mine couple of hours ago. We knew that the main tunnel we were now walking on the ground level was over two kilometers long and couldn’t help thinking what could lay underneath our feet.


At the waters edge we started to get exited. The colour of the water and the surroundings reminded us of the Mexican cenotes, exept these tunnels were man made ”rusty caves” with all sorts of machinery in them.





We slide in, tie off to a pipe that led down, and off we went. The walls were bright and everything was covered with fine white silt that settled down in a minute. Visibility exeeded all our dreams being between 10 and 20 meters from time to time. This tunnel was shallow, just barely under water, and after a few junctions and turns we popped up in a big chamber that had daylight shining in. We’d just discovered an alternative entry/exit to the mine and accidentally traversed in to it. We ended our first reel there and tie it on permanently to a plumbing pipe. We took a quick look around the chamber and noticed that opposite where the day light was coming there was a massive driveway with multiple pipes leadin deeper down toward the heart of the mountain. The visibility was crystal clear and the main tunnel had constant junctions and dead end’s to left and right. We knew we had struck gold and would be back again soon with a bit more gear and a more clear idea what we were up against to.



Back on our little island we had time to get prepared for the second push in the mines. We consulted with one of the family members who owns the mine but couldn’t get much information out since he had stopped working there over 30 years ago but atleast we had a good contact to the family when we needed to get permission for further exploration. We also decided to consentrate only on the second mine that was well worth the risk. From the first trip we had multiple questions in our minds, will the tunnel go or will it pop back to surface? Is there other deeper levels still under the first one? Is the water quality safe to dive in? How big of a complex there is down there?


Second push dive team was consist of two of my friends, Cedric and Fan, who I met in Playa del Carmen during their Sidewinder course out of Protec Dive Center with Patrick Widmann. Both full mine ccr divers and top blokes to hang around.


This time we arrived 03:30 am after a boat ride and a night in the van. We went straight scouting and carried the first load of equipment in the starting point. During the 3 hour scouting around the dry mine tunnels we find two new entry points which now made all together 4 different entries to the underworld. Will they all be connected?



With the sunrise on our backs we entered the mine and started to get ready for the first push dive. This time we had brought with us a kilometer of cave line and we were vigurously spooling it in to our reels while keeping eye on the scorpions, snakes and other critters from crawling in our Sidewinders mouth peaces. First question was, will the main tunnel, we found last time, surface or go deeper. Tieing off to the piping on the sides was easy and we soon figure that we will have work for years in this place. There was constant crossroads and the drive way kept going on deeper and straight into the mountain.

We empty our reels and turned the dive. The scenery, while diving back, watching Cedric and Fan gliding in the distance was breath taking and I could tell their feeling at that moment when you’ve just discovered something enormous and your mind is racing with all the possibilities.


Bottomline Projects Foundation’s team diver Cedric Chan tying off to a stone in one of the massive tunnels in the mine. These stones were rare and you can see how easily the rock flakes away, making tying off even harder.

This time we were all on Sidewinder ccr’s so the moving across the dry sections was much more easier and we were able to do way longer dives. We traversed to the other side of the mine and carried our equipment to one of the new entries we found in the morning. This entry was steaming with bats but the first glimpse under the surface and we were instantly in the adrenalin filled exploration mode again. Checks and primary tie offs and we were once again on our way to the unknown. This time the tunnel was spiralling down and at the 15m level we’d done a full 360 degrees meaning we were right under where we started. Up right there was a familiar looking tight passage that we recognised as the other entry we find earlier. Down right there was a tight restriction that dropped down to the next deeper level. On the left a massive iron gate that was just barely open and led to a ventilation shaft, we decided to follow the main tunnel that kept going deeper and curving in again.



Tying off in this section was almost impossible, the tunnel was cut smooth with nothing to grip and at the bottom there was no machinery nor even stones to tie on to.

Eventually we run out of line and turned back, this time we ascended through the small passage to mark it and then back in and down again to take some images and water examples for later studies.

We had now laid about half a kilometer of new line in and everywhere we turned there seem to be endless complex of tunnels going all directions. We were starting to realise what a 100 years of mining might look like.

BLP team diver Cedric descending through the “Chinese Passage” between the ground and the 15m levels.

Discovering something this big and beautyful beeing hidden and forgotten for decades is the sole reason why we train so hard day by day. The fact that there might not be any blue prints for this mine just makes the adventure so much more appealing and it becomes true exploration. Not knowing what lies around the next corner or when will you be at the end of the last corridore and being the first one to visit the century long history of the three generations of Dr.Bhol familys underground enterprice, is well worth the elevated risk that comes along with exploratory mine diving.




With such world class diving possibilities, the surrounding natural caves, rivers, waterfalls and hot springs, this place needs to be taken seriously and carefully surveyed so that the local community can welcome more adventurous visitors in the region to enjoy the Thailands longest underground tunnels or the crystal clear and warm flooded sections of this beutiful monster of a mine.


BLP team diver Fan gliding through the 5m x 5m highways on her Sidewinder
BLP team diver Cedric descending through the “Chinese Passage” between the ground and the 15m levels.

We have decided to keep the exact coordinates still amongst just a few of us, to avoid less experienced adventure seekers rush in without proper training, in the meanwhile we try to negotiate the terms of the use and survey the


site properly using 3D photogrammetry method as our main tool to understand the magnitude of this complex.





Contact me if you are interested of mine diving training or expeditions in Thailand.

mikko@kohtaodivers.com



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