Velka Vrulja almost one kilometer passages discovered!

Velka Vrulja almost one kilometer passages discovered!
Piotr after 280 m line gone

We are proud to announce over 800 meters discovery in the croatian cave – Velka Vrulja. The new line was laid at the end of April and first week of May 2021 and we – Jolly Diver crew made a significant contribution to this.

It was a real challenge to explore this cave. Entrance is located on 53 meters depth and quickly goes deeper to 75 meters and that is not the only one difficulty. The depth inside varies between 47 and 76 meters so travel requires several significant descents and ascents. Of course the same route back makes pretty sensitive saw profile for decompression consideration.

We would like to share with you some backstage aspects and present a bit this cave.


No maps = flexible planning

Velka Vrulja almost one kilometer passages discovered!
Small but own gas filling station

Our preparation started in Poland much earlier, filling gas bank, rope supplies, check dives, fine tuning of our configuration with focus on upcoming dives.

Crucial was to gather as much information as possible before first dive. We had no idea what we will find behind the corner…

Any information is worth it’s weight in gold. So here many thanks to Wojtek Filip for reminding himself and sharing his experience with us. Wojtek is the only one person we were able to reach out who made diving in this cave before. That helped us to understand and imagine at least a bit what we may expect, but even he did not remember exact location of the cave, so… next challange. Anyway cave begins at 50m, goes down to 70 meters and continues. It does not sound as easy peasy dive. We had to be prepared for various scenarios. Going to Croatia we were ready for dives slightly over 100m depth, but rather focusing and assuming that cave will unfold itself horizontally.

Finally, right after our first dive we had to rely on our own discoveries and had to tune up the plans every day basis on prior discoveries. That was really huge effort we did not thought about before. Analysis of the depth profile, ENC2 Navigation routes, watching again and again the movies from the dive to find potential continuation and to plan the next dive. It was really hard work, including line calibration, gear preparation, filling the tanks it was taking absolutely whole day.

Due to huge spaces, whimsical visibility, lack of current that could help us recognize correct direction of exploration. We had to identify potential areas to be checked first, then dive and realize that most of the spots we identified are just some cracks in the rocks, bigger recesses in the walls or just over 20 meters width corridors. So that’s how after 2 days of researching we have reached out to the point when Ula labeled one of the places „Hope Chamber”. That was the last one and only one reasonable place, where the cave could potentially continue. Even though a day before we were watching this place and it seemed like just another big chamber that turns back and goes back to our line, we decided to give it another chance and yes – it was bull’s eye. „She” let us go further, so yet another 280 meters of line was laid.

Velka Vrulja almost one kilometer passages discovered!
Every line was calibrated and marked
Velka Vrulja almost one kilometer passages discovered!
Empty reels at the end of the trip


Almost a day underwater

Velka Vrulja almost one kilometer passages discovered!
Hatchery of Aliens

During the week we made 6 dives in Velka Vrulja cave and spent in total almost one day underwater (unfortunately mostly on a deco in open water). We started our activity right after our colleagues from Slovenia and Hungary have finished their dives. We were lucky to leverage their experience and benefit from completely new line, that we could trust on our dives. Our first trip was to check conditions, line, depth and measure, using Seacraft ENC2 console the distance. The visibility on the entrance was poor – around 2 meters maximum and on a distance of first 150 – 200 meters it did not go better anymore.

That was really great idea to lay the line not only in cave, but put a direct connection to the shore. It is over 200m extra line, but was making our dives much much easier and more effective especially in last days, where visibility not only on the beginning of the cave, but also in the sea was simply poor.

Robert, Gyula, Atilla big thanks to you again!

On the first push dive we found an interesting formation at the ceiling. It looked intriguingly. Strange hanging cocoons. We went further, through small squeeze, and corridor gets back wider and wider. I select right wall, it turns right and again right. I can see something unusually white, what’s this?. Few seconds later confusion ceases. It is our line, and again cocoons. Wow, that must be aliens’ cocoons! 265 meters of line lied in a cave, and a bit disappointment because I still have 35 meters rope left on my reel, but not everyday you are finding Aliens’ Hatchery, so we end dive very excited and pleased from new discovery.

Only during 3 of our dives we were pushing exploration and laying the line. We put in total 720 meters (265m+175m+280m) of ropes. The line was calibrated each 5 meters and marked with a knot and a label every 20m. The huge spaces and low vis made impossible to easily speed the scooters up and push forward. We spent 2 long dives only on researching and looking for possible continuation.

Conditions in the cave were changing every day, especially the visibility at the first 150 meters was worser and worser. Considering fact that at the first day it has been  „awesome 2 meters”, we made our last dive driving carefully just right by the line to not get lost. But few times Velka Vrulja also surprised us positively. At some spots visibility was improving on a limited distance, so we had a chance to enjoy this amazing art of the nature at least a bit.

Low visibility made also impossible to check and properly map the beginning of the cave. Corridor width presented on the map below is assessed to be minimum 6m, but it definitely has to be much wider.

Velka Vrulja almost one kilometer passages discovered!
New EOL is here
Velka Vrulja almost one kilometer passages discovered!
Driving through the corridors


Difficulties to overcome

Velka Vrulja almost one kilometer passages discovered!
Shit also happens

Not everything was perfect. Exploration dives are much more demanding than tourism cave dives, even advanced cave tourism we are usually conducting.

Lot of unknowns requires planning to be more flexible, however some elements are more or less predictable. We had basic information from Wojtek about possible strong flow (fortunately not occurred this time). However the visibility, especially at entrance and first 150m was awful. The visibility was changing in the deeper parts, but it was far from stunning. That was major challenge in huge passages and chambers. Conditions were noticeably favorable in narrower corridors.

Sometimes our gear did not cooperate with us as much as we wanted. Look at the reel picture on the left. That was caused by simple small mistake made during reel preparation. That mistake costs us few extra minutes on 70 meters depth and reel was out of order for the rest of dive. Fortunately as real technical divers, we had equipment duplicated, so backup reel got into the game.

Ultimately we had to find the way to make safe exploration dives as a team. It differs from usual cave diving. Each of us had own role and tasks. Both of us had to adjust to the conditions that cave was imposing on us. Everything was yet more challenging because during the dives we were conducting measurements and every move was reflected on Seacraft navigation. We aimed to make dive tracks as much repeatable and comparable as possible. This was very valuable time. We have not only verified our equipment and configuration in these demanding dives, but also found new way of usage for some non-cave gear i.e. wreck strobe.



Equipment used during exploration

Velka Vrulja almost one kilometer passages discovered!
Some exploration gear
  • 2 JJ-CCR reabreathers
  • 2 Seacraft Ghost 1500 as primary DPVs
  • Seacraft Future 1000 as backup DPV
  • Seacraft ENC2 navigation console
  • 2 GoPro cameras
  • 2 SANTI Elite dry suits with warm heating
  • OrcaTorch D950V video light
  • TROJAN strobe classic


Velka Vrulja exploration step by step

This cave was discovered and its exploration started at 2013 year. We found vestigial info and name of the cave that we did not hear before in the internet by the way of preparation for diving in another Croatian caves. Further research led us to the map made by Wojtek Filip, and this is how everything started.

We are not aware of any other exploration activity in this cave happening after 2013. There is one quite fresh line on the distance of first 70 meters in the cave, but we don’t know who it belongs to. We are looking for contact to the owner of the line to exchange our experiences, as the cave behaves differently than other nearby systems.

Team 1:

  1. Wojtek Filip (Poland)
  2. Luca Palezza (Italy)
  3. Andras Kuti (Hungary)

Short summary: according to information from Wojtek team put line on the distance of 109 meters and made first measurements and created a map – an unique historical sketch of the cave.  Fragments of their rope are still available at the entrance, as well as entry corridor of the cave.

In spring 2021 5 divers from 3 different countries met in Croatia to take up exploration of Velka Vrulja.

Team 2:

  1. Robert Anžič (Slovenia)
  2. Nagy Gyula (Hungary)
  3. Attila Incze (Hungary)

Short summary: team did locate the cave entrance and made an effort pushing the cave to around 175 meters as well as making an excellent job connecting cave entrance to the shore.

Team 3:

  1. Ula Wróblewska (Poland)
  2. Piotr Dudziak (Poland)

Short summary: added 720 meters of line, found 3 huge spaces (chambers), some bypasses and side tunnels. We reached out maximum distance of 680 meters from entrance. The effects of survey are presented on the plan below (distance of Team1 and Team2 are also marked).


Velka Vrulja almost one kilometer passages discovered!
Nice rock to make a knot
Velka Vrulja almost one kilometer passages discovered!
Smaller passage = better visibility


Velka Vrulja plan


Short information about Velka Vrulja:

  • maximum depth – 76 meters
  • average depth – 60 meters
  • actual passages length – 800 meters
  • major risks:
    • possible strong flow,
    • very low visibility,
    • large spaces,
    • significant depth

Velka Vrulja almost one kilometer passages discovered!
Time to use strobe
Velka Vrulja almost one kilometer passages discovered!
Let’s check what’s there


That is amazing that in 21st century there are still places like this waiting for its discovery and we, divers do have greatest chance to become modern Columbus,  Amundsens or Armstrongs on the earth.

to be continued….

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