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Diving in the Opal mines of Dubnik


Only a few places in the world have a thousand year old history of human activity connected with diving. The opal mines in Dubnik – located close to Presov city on eastern part of Slovakia is one of them, and we chose that place for our dive site because they are unique.


The first mining of opals in this place around Dubnik was in the 11th century.

At that time they were already extracting the precious opal and because of that a Dubnik is the oldest and the largest opal mine in the world.

Additionally these are the deepest mines to acquire opals.

In the 18th century there were about 800 workers and they built over thirty galleries with a total length of over 22km (13.75 miles) by hand.

If we want to find something similar, we have to go to Australia to places like Lightning Ridge, Coober Pedy or Mexico’s Zimapan.

The other locations are in the Americas especially in Honduras and in USA, Brasil, Russia and Germany.

However, the quality of their minerals is not that good as that of Dubnik’s stones.

One of the Dubnik rarities is the “Vienna Imperial Opal” also known as a “Harlekyn” which is the biggest opal in the world with a weight of 594 grams (20.952 oz) and its value is estimated at 500,000,- US Dollars.

The next valuable stone is “Burning of Troy” (about 50,000,- USD) which is now a part of France’s coronation treasure collection.

In spite of the tremendous output from these mines, they were shut down in 1922.

Shortly after the mine closed, opal thieves entered and destroyed what was left.

Opal Mine 1

Dubnik’s underground spaces are not just great for a precious stones, they are also perfect as a winter home for bats – it is the biggest european winter home for more then fourteen different kinds of bats. During the winter there are over 4000 bats living in the caves.


After traveling 670 km (420 miles) from Prague we were sitting at the location with Vlado Konrad, the local boss by late afternoon, and already talking about situation underground…

Vlado is a very friendly person and we were happy to go with him to see the dry parts of the main cave.

Dubnik’s main cave is not all underwater the underwater part is only a portion of Viliam’s gallery with a intricate labyrinth very close to Fedo’s gallery.

Corridors are on three levels with a depth of 15, 30 and 50meters (50, 100 and 166 feet) they are all connected by vertical passages, stairways, and a main gallery Fedo.

The visibility in the slightly acidic water is absolute – limited only by flash light power.

The maximum depth of 67meters (223 feet) depends on the water level.

We’ve planed one dive for each day. Transporting our dive gear in to the water wasn’t so easy because of the very intricate corridor system.

We had to travel hunched over three times for a half kilometer (1600 feet) from the underground entrance with all our dive equipment threw a slippery corridor with a very low ceiling using only light from our flash lights.


And believe me, every slip or fall with a load of tanks hurts…

Finally the dive time comes and we couldn’t wait to get wet.

We were so excited, we finally got into the entry passage with our last load of equipment for the last trip through the long, intricate, dark and already somewhat known corridors all the way to our dive gear storage place.

Dive briefing and getting dressed was very difficult and uncomfortable because of high humidity and the constant annual 1*C (33,8 F) air temperature.

After finishing all the procedures we finally got into the incredible, crystal clear, cold water.  Our dive path was going from the crossroad point on right side through the 6 meters deep (20 feet) tunnel.

Roughly after about 20m we had to snake through the partially collapsed walls which were built so many years ago.

The water was not very muddy…so-far.

Then we were amazed by “CICVARS”(that is local name for formations growing from the ceiling) in the corridors.

At the end of the corridor there were steps leading down to the next section – horizontal tunnel at 30m of depth.

When we arrived at the next tunnel all that was left was a heavy wood frame from the ventilation door.

We were descending deeper and deeper.

Threw twisting steps the corridor continued until we entered into the shaft named “Fedo”…

In a world of powerful diving lights, we were suddenly in a spacious hall.

From the darkness the wooden construction of the shaft showed up with more than a hundred year old patina.We were moving very slowly to keep from stirring up the heavy sediment.

With great respect we looked down into the very deep shaft.

Concentration on our own movement was number one, because just one bad move can very easily ruin extremely clear water and turn it into an impenetrable fog.

The main corridors are lined with a many different reels and crosses witch are marked with arrows. For movement in cathedrals around “Fedo” and in lineless spaces we are using our own reels and jump ropes…

“The visibility is still very good, because of the gentle movement of the other divers.

We are leaving the shaft through the horizontal corridor (-100feet) in the direction of the vertical passage which is at the end of one of the circles created by the flooded tunnels.”


There were a lot of wood boards on the ground a front of us and between them you can still see the foot prints of horses.

Les then eighty years ago horses were working here and pulling heavy loads of earth through the dark intricate labyrinth.

We decided to ascend through the vertical tunnel where the visibility was about 20cm (not even one a foot).The ascent went well in a rattle of bubbles from the open circuits of other divers and it was very enjoyable.

“I’m so excided and I cannot wait for tomorrow’s dive which starts in the same vertical tunnel but the descent headfirst…”

At the end of this first dive we took a look (during the decompression at -6m) on the left side of the main crossroad and we enjoyed the colorful scenes in that intricate corridor system…

Carrying all of our stuff back outside was not been a big deal, after that great and enjoyable diving experience.

It was neither a long nor difficult way out of the darkness and it was not getting in the way of our excitement.

For the rest of day we were just exploring the mine’s dry site – looking for some opals in many extracted earth piles and talking about today’s dive a planning the dive for tomorrow.

Currently “Opalove bane s.r.o.” is taking care of the protected “Dubnik mine”, which is 6 ha (14,8 acres) of property including the underground spaces, corridors, shafts, tunnels and technical monuments.

 Visitors and amateur opal hunters are allowed to visit the dry area of the mine during the summer season to look for opals after paying a local fee.

There are two circles for diving in Dubnik which are about 600m (2000feet)long.

But because of the high risk and overhead, cave diving with the right configuration, special training and experience (certification) are needed!!!


For Sunday we had decided to go into a non marked and lineless corridor at -40m of depth (133feet) which is going to the mezzanine all the way into “Fedo”, which was discovered two years ago by a couple of divers Hasa & Skovajsa.

After the descent to the main crossroad – Marek was the first who penetrated – head side first – into a small slot and the rest of us were following him down one by one.


The last one to descend into the vertical tunnel was Petr. He was going down just by instinct with absolute zero visibility…I did not envy him.

To go down into a chimney with a mix of rolling bubbles, dirt, ooze and mud is a courageous achievement.

Going down very slowly, deeper and deeper from the connecting corridor on our own reel was nice because this area has been penetrated by very few divers (you can count them on one hand).

The ceiling of this tunnel is still almost untouched, more then two feet long decoration of “limonitas” curtain.

Marek has been leading us through a corridor which was known only by him. I followed him about three meters (10feet) behind with great admiration of his brilliant movement in a space like this, with a lot of ooze it can get very cloudy easily…

He did not stir up any sediment when moving, so I had a great chance to take a lot of pictures in great visibility.

I could not believe my eyes when we came to a spot with rails which lead us back to the shaft “Fedo” where it connected to a bizarre underground railway station.

There we were floating like in the air and unbelievably looking at all the rest of the human activities which made this county a hundred years ago, known and famous all over the world.

The space in the shaft “Fedo” is very unstable because of a collapse above it.

It is impossible to dive to the bottom with a open circuit system to discover corridors at levels -50m (166feet) deep.

This might possible for divers with rebreathers which are not making bubbles…

Because of this we were just documenting details of the shaft’s exterior, rails and adjacent corridors.

The wooden supports here are in much better condition then in the tunnels at -30m (100feet).

For example you still can see pulleys on beams.

The wall’s colors were changing from red-brown to green-gray until they were almost blue and we were “quietly” astonished by the incredible and amazing scenery.

On the other hand our way back was like a “blind wander” by touch in absolute zero visibility.

But thanks to all of our training, drills and a lot of practice it was not a big deal for us at all to get safely back to the surface in the entry tunnel.

For our dives we’ve chosen as a BG: Nitrox 32 in double sets 2x18L and 2x12L with 80cuft stages. Jakub dove with his rebreather  CCR CIS LUNAR.

And we used argon (as usual) to fill-up our dry suits because the temperature of the water was 3st.C (37,4 F)


Our maximum depth for each dive was 34m (112 feet) with a dive time of 70 min.

Over the hundreds of dives on wrecks, in caves, seas or in fresh water are still the memories of atmosphere and experience from diving in opal mines in Dubnik. This still has a first place in my private diving life.

Stephan Whelan
Stephan Whelan
Stephan is the Founder of His passion for the underwater world started at 8 years old with a try-dive in a hotel pool on holiday that soon formulated into a lifelong love affair with the oceans. In 1996 he set up and has grown the site to be the most popular diving website and community in the world.