Report on weekend 10-11 September 2005

Within the framework of the SELAS Caving Club's ongoing project of exploration at the Dersios sinkhole in Arcadia, an expedition was planned for 10-11 September with the following aims:

Ι. Survey from the second sidebranch to the large chamber / junction at -151m (green on chart)
ΙΙ. Survey from the end of the surveyed section in the sidebranch until the third sidebranch sump (in red colour)
ΙΙΙ. Survey from the large chamber / junction at -151m to the beginning of the third sidebranch sump (yellow colour)
IV. Cave dive with survey equipment in the second sump and evaluation of continuation potential. (blue colour)
V. Cave dive with survey equipment in the third sump (loop closure - the loop will be more than 1km long) (blue colour)



click on image for enlargement



So we all got to the plateau at some point on Friday evening and all four cars made their way to the cheesevault next to the entrance of Dersios. The electrification of the plateau had reached the cheesevault and we now had the added luxury of electric lighting at night. We got ready for bed intending to organize the expedition the next morning during breakfast. The aims of the weekend were well known. The survey team would also de-rig the new section, the diving team would only deal with the diving. After a good dose of omelette (with sausage and other goodies) the diving team (Nikos, Komninos and Panagiotis) set off straight for the second sump while the de-rigging team (Nontas, Maggie and myself) set off for the sidebranch a little later with Olga and Panagiotis.

Reaching the point a little before the scree slope linking the two sumps (point 0504 on the survey) we found the water very much higher than on all previous visits coming after the original emptying of the sump. The water was up to chest height and the low passage to the scree chamber was only a little more than 40cm from water to ceiling. We made the decision to go for it - seeing as we would be getting wet anyway that day and I got into the water on my back to get through. I made it through and up the scree through an even smaller gap and waited for the others. Approaching the chamber from which the passageway began we realised that we had lost the passageway in the five weeks since the last visit - it had sunk once again under the water.

In mythology, in Hades, the Danaids perpetually filled a leaky pot with water which never filled... in the Dersios sinkhole this year, we have been perpetually emptying sumps which refuse to remain empty. Next year will be different - we will approach the whole sump thing differently.

We stayed inside for a little longer - Maggie took Panagiotis and Olga round the cyclical route through the sidebranches and then a little deeper, while I made my way out into the sun with Nontas. Maggie's team found Panagiotis on the way down, the first sump was full as well and needed a dive to get through. Nikos and Komninos had gone through and deeper to make the dive in the second sump.

While we were outside with Nontas, two young shepherds passed, brothers with a shared flock and we got chatting with them about the area and about the sinkhole itself. The information we received was the usual mix of myths, folklore and local knowledge about the area around the sinkhole. An important piece of information is that from the beginning of the summer it had rained only once - and that for only half an hour. This shows that the sumps re-fill without rainfall - something to keep in mind in the future.



Nontas talks to the shepherd while still in the wet and cold neoprene outfit - commitment to information collection requires local info to be gathered to come before personal comfort. In the background, the cheesevault.

We began to prepare snacks and waited for the diving team to come out so we could begin to make the pasta. At some point Theodossis came as well and brought wine and set the fireplace alight. When the diving team came, we put the food on and listened to their news.



Theodossis gets the fireplace started

As we had been told - the boys passed the first sump by diving - Komninos' first cave diving experience, may he have many more! - and headed straight for the second sump for Nikos to dive. Nikos dived successfully and took survey data within the sump (which is about 30m long). The data will soon be added to the rest of the cave and announced. Nikos then walked to the next sump about 150m away. He had a look inside and it seems deeper than the rest. Nikos then made his way back to the second sump taking care to look for return routes which would bypass the sump, but found none. The next goal is now to empty the second sump and dive the third to look for continuation.


Two divers

In 2003, the second sump seemed to be impossible to empty but now, with the accumulated experiences which we have gained both as individuals and as a club, it seems that it will be possible to empty the second sump despite the small but continuous influx of water.

On the second day, most of the team set off early for Athens so I was left with Nontas and Panagiotis to go do some rescue work in the cave. First priority was to get the 120m of hosepipe out of the sidebranch so we didn't lose it when the sumps get completely filled again. Next, there was a need to re-rig the pitch after the lake in the chamber with the stalagmite. As we set off for the entrance we found some friends of Thoedossis who had come to join us from "Spena". We were happy to have the opportunity to share our descent with Yiannis and Makis, both active members of "Speleology of Nafplio".

We went in and re-rigged the worn rope and went down to the now completely empty first sump to close the taps on the hosepipe to ensure the hosepipe didn't fill up with air again. The kids from Argos left for outside and we gathered up the hosepipe from the sidebranch and hid it away above ground in a place where the winter waters shouldn't reach it.


So what's left now? Well, we need to de-rig the whole cave before the winter starts and that includes getting all the rope out of the sidebranch - something which will need another cave-dive.

Weekend at Dersios

In the framework of the ongoing exploration project which began in 2003 a small team of four found ourselves on the Palaiochora plateau at the weekend; there were three cavers and one caver-quartermaster in charge of the food.

We went up on Friday and slept in Tasos' cheesevault about 250m from the cave entrance.



Internal view of the east side of the cheesevault

The purpose of the expedition was to dive the second sump and see what the potential for continuation of the cave through there would be. Our cave diver Nikos Mitsakis had dived both the second sump and the sump in the third sidebranch in 2003. Both come out in a dry section. The section beyond the second sump reaches a third sump a few meters further on, and the section beyond the sump in the third sidebranch ended at the bottom of a pit after quite a distance on foot.

We had begun to empty the sump in the first sidebranch at the end of last week. Nikos had dived here last year to a distance of about 70m without finding a way out, and again last week where he discovered a dry dome with a fissure leading off it too difficult to attempt with the bottles on. The idea was to empty the sump and have a look at this fissure for ourselves.

Nikos and Komninos had put on their neoprene suits ready for the dive. I don't have a neoprene suit, so I didn't wear one. On getting to the entrance to the second sidebranch, I saw both the boys waiting for me there with huge smiles on their faces. Yeah, I was taking my time and they were criticising - or so I thought... they asked me to listen to the hosepipe, again with the huge smiles - I listened... water! Running water! The hose which had been set to empty the sump was still emptying after six whole days!

Almost running, we made our way to the chamber at the end of the sidebranch and feasted our eyes on a most beautiful and satisfying spectacle: passage! Where one week earlier there had been only rock and water, we now saw the water level had dropped by about a meter and new passage opened up and beckoned us into the unknown.

The other two strode off chest deep in water into the unknown and I stayed behind waiting for them I don't recall how much time passed - but at some point they returned, dressed me as fast as possible in Komninos' neoprene jacket, put rope into the sack, left unnecessary weight behind and we all three of us now leapt into the waters. The water was cold enough, but the neoprene is rather good in these conditions, no doubt about that.

This new passage that used to be a sump had a meandering route through chest-high and neck-high water interspersed with completely dry parts. We walked through sections reminiscent of canyons, totally sculpted out of the rock by the waters' passage. We finally reached a large break-down chamber where the sump would empty out as a waterfall in the winter. From there, a few meters further on we got to the first descent. The boys had got this far without me when they had turned back for rope - now I would be taking part in real exploration into the unknown for the first time!

After the first descent, the cave takes a small turn to the right, turning from a course of almost directly south back to the usual sort-of westwardly course we were used to in Dersios.

We went through some meters jammed in between two different rock types - one was stratified horizontally, the other had stratification at an angle of about 55-60 degrees. In between the two, in a gap of about 50cm to 1m the water would flow in the winter. In between the two, either walking or climbing, we continued to push into the unknown.

After a little while we reached another descent which needed to be rigged. This one needed an anchor to be placed also. It was about here that we bgan to run out of rope… we had not in any way foreseen such a long and deep continuation to come out of the sump and all the rope we had with us was of short length and needed to be knotted together. After the second descent, the going was similar to how it was before - a little walking, a little climbing and on to the third descent...

Here, we turned back for the rope we had used to rig the first descent, which had a positive incline and could be easily climbed without rope. I stayed back and the boys carried on as far as the rope would take them. According to their Suunto watches, we were about 120m below the entrance at the point where we turned back.

We turned back to the entrance, full of enthusiasm and totally ready to devour any food placed in front of us!



The well-stocked cheesevault's stores

Waiting for us outside was Niki, probably overjoyed at the news that we were out while the sun was still shining. She prepared the evening meal with the help of Komninos. Theodossis came up from Tyros with walnut cakes and wine. There was no disappointment that the cave dive did not happen: our efforts of the past month had bourne their fruits in the form of new passages. We figured we had discovered about 300m of new passage but the length was less important to us than the fact that the route was beautiful.

Still, we had a lot of unanswered questions. Where does this new passage go? How much further would it go? Would we end up at the top of the pit Nikos had seen in 2003 or somewhere else? Which way does the water go in winter: this way or down the known route?

We all slept soundly with the smile of success on our faces in the company of the little mouse we had found in the cheesevault's cupboard. This was no doubt a cousin of the guys we had seen a few weeks before in the cave - their colouration was identical.

We woke late the second day and did some household chores in the cheesevault. Niki left for the beach with Theodossis and left us to busy ourselves with the survey of the explored section and the completion of the exploration. We commenced our descent de-rigging the unnecessary ropes from the initial descents at the entrance hoping in this way to end up with enough rope to complete the exploration.

In the chamber before the sump we discussed the survey strategy and set off. The first 120m or so were tough, with about 6m between each station and every other station requiring someone to be motionless in the water. The long time in the water was a little tough. After the waterfall Dersios opened up and we were out of the water again.

We reached the spot where I had turned back the day before and the guys rigged the third descent again replacing the completely exploratory rigging with something more sturdy. After this we got to the fourth and last descent where the boys had tried to go down without rope the day before, through the narrow gap between the rocks, but this gap opened out making it impossible to continue. So here it was that the last rope was rigged and the last descent was made in this new section. After the descent, to the right, the cave continues, walking, at a depth of about -140.

Nikos went off down the walking section and Komninos and I took the last measurements on the survey. The walking section ends up at a sump and in the sump we could see the diver's guideline. We had closed a circular route of over one kilometer (it is about 500m to the beginning of the sump from the beginning of the second sidebranch, whichever route you take - new or old.

We came out satisfied and began to prepare to go down to the beach and meet Niki.

Some words about the new sections:

Newly explored / newly surveyed sections (in July 2005): 477m
Newly explored sections beyond the surveyed section: ~100m
Overall length of surveyed section (31 July 2005): 1.381m
Estimated length of explored section (31 July 2005): ~1.700m


Tasks still needing to be done:

Survey of the final section from the last pitch to the sump in the new section.
Drafting of the survey.
Re-survey of the old cave
De-rigging

There are no photos of the new sections, cameras were part of the unnecessary weight left behind. Clicking on the surveys will open up bigger images.



25 July 2005





31 July 2005 plan





31 July 2005 projected section from 285 degrees

Report on the expedition of 30 and 31 July 2005

As the first sump was still underwater, we explored and surveyed new parts of the first sidebranch. The first sidebranch was connected to the third sidebranch, after quite a few meters (400+) of new exploration. Details coming soon.

The expedition was manned by: Nikos Mitsakis, Komninos Boutaras, Stelios Zacharias and Niki Hatzilia.

Report on the expedition of 24 and 25 July 2005:

On Saturday the heat got to us a bit so we went for a swim first and then for a look-around in the area. Our look-around had some promising results and brought to light a number of places well worth looking into in the future.

That evening, the expedition cook ate and slept in a cheesevault near the sinkhole, something which allowed us to sleep a little beyond dawn as we weren't woken up by the heat.

The sump in the second sidebranch had emptied and was surveyed by Komninos and myself, allowing us to close a loop back at the entrance lake. The loop is about 250m long and we got a 5% declination in doing so. This will no doubt change when we confirm the survey data next week.

In the end it was one reading on the clino which was made wrong. When this was corrected the loop closure gives an error of less than 2% and these new figures were used in all surveys after 30 July.

The first sidebranch is most probably the old river bed - it has the same direction as the sink-hole's main chambers but it ends in waterlogged sections at about -40m. We started an effort to drain this sump also, using the 120m of one inch hose in an effort to allow access for non divers to the narrow fissure which Nikos had seen at the end of the sump the week before.

The first sump was passed with difficulty as it had filled again with the waters from the sumps above it, but the team of Nikos-Giota-Panos managed to make some repairs to the 1 1/4 inch hose and restart the draining. For this reason, it was not possible to dive the second sump.

The expedition was manned by: Nikos Mitsakis, Komninos Boutaras, Yiota Kafetzi, Stelios Zacharias and Panos Papasotiriou.


Results of the survey conducted on 25 July 2005:
The results are presented as projected elevations, using the vtopo programme (link in sidebar to the right).





The entrance is at point Α
The first sidebranch is points Β-Γ
The second sidebranch is points Δ-Ε
The union of the two can be seen in blue
Point Ζ (sump) remains underwater as at 25 July 2005, but efforts are being made to drain this sump also and open new routes.

Report on the weekend of 16 and 17 July 2005

In brief, the weekend was memorable on account of the water, the hoses and the food served at the entrance to the cave, which I unfortunately missed out on as I wasn't taking part in the mission at all.

The siphon in the second side-branch is almost empty and has already given about ten meters of new passage which lead towards the initial (walking / swimming) part of the sump in the first side-branch which had also lost a little bit of height.

It would be possible to empty the first sidebranch's sump into that of the second, and from there to empty both deeper into the cave. Another 50m of one inch hose were taken into the cave for this purpose. It is now possible to dive the sump in the first sidebranch without going through the squeeze through the gours.

The first sump had almost filled up owing to the teams efforts to empty the higher sumps and it was necessary to re-empty it: this task occupied the team on the second day of the expedition.

Finally, there was a little exploration done in the field by Panos, who was led by a local to a "bottomless" pot hole of all of 8m depth!

The following members of SELAS were present: Nikos Mitsakis, Niki Hatzilia, Yiannis Vavourakis, Marianna Manolatou and two recent graduates from our annual seminars: Panos Papasotiriou and Nektarios Servos.

Some info about Dersios:

Between the years 2003 and 2005, cavers of SELAS club have been extending the exploration done by French teams in the 1970's in the "Dersios" sinkhole of Arkadia. The sinkhole is at about 750m altitude and presents technical difficulties as there are many parallel passages ending in flooded sections. These have been explored by emptying the sumps or by cave-diving. The expeditions of S.EL.A.S. have doubled the depth of the explored cave (-160m) and more than tripled its length. I have been involved in the exploration since 2004.

The general lie of the land around the sinkhole (which is visible about two thirds of the way to the right just this side of the road) is captured in this picture.