We are proud to announce that the Croatian cave – Velka Vrulja is now 570 meters longer and one meter deeper. Currently its maximum depth is 77 meters. We have discovered, explored, laid line and mapped more than a kilometer of this cave in total.
Read more about our previous exploration activity in this cave: Velka Vrulja almost one kilometer passages discovered!
We went back to Velka Vrulja with simple strategy, to check possible continuations identified on the video recordings from previous dives.
We knew that further exploration of this cave won’t be easy…
New challenges appeared
This time we made two dives spending underwater 10 hours. While searching for a cave continuation, we have found some really impressive karst formation sites. One of them is located on the other side of chamber we have called „Lu(c)k corner” previously. That’s pretty fortunate name of this spot. It has multiple connotations and there is a little bit more to that name. Maybe good topic for another post, but just enough to say, continuation of the cave was found right after the Lu(c)k corner.
We had to revise our risk approach – especially for gas management based on open circut bailout. Also the weather was not helping – hot days came. In short words, the only solution was to get up very early and take yet more tanks…
Heat on the surface means also water temperature is increasing, at least in open water section. That seemed to be an advantage, especially that it was about area where we spent most of the time on deco, but 25 Celsius degree at 3m stop turned out too hot and made our decompression a bit more complicated.
Cave profile – Saw type
Velka Vrulja has pretty demanding profile, so called „saw profile”. Significant changes of the depth occurs five times one-way and are up to 30 meters difference. In total, you have to reach a depth of over 70 meters ten times ascending between them even up to 47m! Of course this factor has significant impact on the plan of the dive.
Deco and total dive time
The average depth at which we operate in the cave was 64 meters. Cave entrance is located on the 50m depth. That impose quite long decompression. Each time we spent in overhead around 75 minutes and then over 3 hours decompression.
Velka Vrulja – current plan
As a Jolly Diver team we explored over 1 km of Velka Vrulja corridors on average depth of 65 meters. While searching for a continuation, we’ve found amazing rock and karst formations. Due to the size of the cave, and consistently weak visibility we expect more similar discoveries on upcoming dives.
You may take a look on summary of previous exploration to compare the maps and see how much progress we did: Velka Vrulja almost one kilometer passages discovered!
Short information about Velka Vrulja:
- maximum depth – 77 meters
- average depth – 64 meters
- actual passages length – 1 350 meters
- major risks:
- possible strong flow,
- low visibility,
- large spaces,
- significant depth,
- saw or „jojo” profile.
Equipment used during exploration
- 2 JJ-CCR reabreathers
- 2 Seacraft Ghost 1500 as primary DPVs
- Seacraft Future 1000 as backup DPV
- Seacraft ENC2 and ENC3 navigation console
- 2 GoPro cameras
- 2 SANTI Elite dry suits with heating undersuits
- OrcaTorch D950V video light
- TROJAN strobe classic
to be continued…