Thursday, August 30, 2018


Moonmilk. Bats. Artefacts from 1800s. Still, inexplicably, all the other 15 participants have cancelled this excursion, including one of the guides. Why? Last nights party? Perhaps, the last guy to cancel says he partied too long. Or maybe it is the rain. It has been raining cats and dogs.

But, there is still one guide, Barbara, an Austrian cave scientist from Vienna. And one guest, me. I'm eager to visit my fourth cave on the Eurospeleo trip. I've spent a week here, but decided to have a day off between cave visits, to rest, to dry clothes, to work... but this means that I didn't want to cancel any of my excursions.

Amazingly, the rain stopped as we headed off to the trail. Now we had green, lush forests and good weather.

Did I say trail? Obviously there is no trail. For this cave, we needed to hike up a bit over 200 meters on a steep riverbed. And while the rain had stopped, all stones were wet and slippery. And loose; we had to be careful to not cause a rock fall. And sure enough, we did not cause a rock fall but next to us in the forest we hear rumbling noise. We catch a glimpse of a rock speeding down. I look for the sides of the gully we are on, to find a safe spot in case we are the target of the next rock. Fortunately, there is no more rock fall.

Nixlucke is a small (length: 177 meters) cave on the hills under the Feuerkogel cable car above Ebensee. It has four entrances, although only one is passable. Three medium sized cave rooms open up right from the entrance, the first one being the largest. One of the entrances is at the top this room, providing some light.

In the 1800s Nixlucke was mined for moonmilk, which at the time was believed to have healing powers. The upper parts of the cave have been largely cleaned of moonmilk, but the lower parts still have some. 

Getting to the lower parts is not easy for me, however. The other end of the cave forms a pit that one has to descend with rope. Which I had not done before... but it turns out that it wasn't so difficult. We reach the wet bottom of the cave, with fine clay mud and moonmilk covering most surfaces. And then climb up, with the rope being needed only for a part of the ascent.

Overall, very nice small cave, with interesting moonmilk and texture features on the cave walls, and good practice for me. And hiking up to the cave was much needed exercise, even if one had to place steps carefully. I'm very happy that I got to visit this cave.

More information and access instructions Nixlucke can be found from here.

Bat waking up:

Cave entrance:

Views from the hike:

Setting up rope for the descent:

Tools of the 1800s moonmilk miners:

Cave texture:

This article has also been published at TGR. Tämä artikkeli löytyy myös suomeksi Relaasta. See other caving articles at the site.

Photos (c) 2018 by Jari Arkko. All rights reserved.

Dachstein Mammuthöhle

My first visit to a large cave system, in the wild. An all day adventure with geology lessons, and climbing steep and slippery clay tunnels!

Dachstein Mammuthöhle spans 67 kilometer and an altitude difference of 1200 meters. But really the mammoth size comes across best in the tunnels: these are crawl holes or even metro tunnels, they are massive empty veins running through the mountain, and you'll feel small. Not sure how big the biggest tunnels are in numbers, but at least 10 x 10 meters, if not more...

This cave is also a show cave. We started out adventure from that part; even the show cave is impressive and well worth visiting. The tour covers a kilometre loop inside some of the biggest tunnels in the cave.

The cave is also very cold, just 2-3 degrees. There's even some ice. And while there was plenty of climbing due to the 25-30 degree bedding plane the cave rests on, big parts of the cave can be visited without having to resort to ropes and ascenders. On our tour we had to go through a very narrow passage, which caused my claustrophobia nerve to get a bit panicky. This was a low section for maybe 15 meters, low enough that I couldn't go through with my helmet and had to push it in front of me. A little tight even otherwise, but I didn't have to take my small camera out of my front pocket. Still, unnerving when you are far into this huge cave.

Our guide in the cave was a geologist, Lukas Plan from the Vienna Natural History Museum. We focused mainly on signs in the cave of how it was formed, and what had happened in the past. As a karst cave, it was obviously created through chemical reactions and water. But still, there are many questions. Which way did water flow on this tunnel? Sometimes water flows uphill in caves, if the particular part of the cave is under the normal underground water level the tunnels and the water they carry can zigzag up and down. At Dachstein Mammuthöhle there's an added complication of the tilted bedding planes in the rock, hence tunnels being forced be tilted as well.

We looked at wall formations for signs of water direction. It turns out that small depressions in the walls are formed by the flowing water, and the steepest walls in those depressions point to the direction where the water is coming from. And the size of the depressions correlates with speed of the flowing water. A long time ago this had caused people to incorrectly think that cave passages carried water flows equivalent to their size times the observed speed. In reality, the passages tend to be filled with silt, rocks and other materials and the usable part of a tunnel may be a small fraction of today's tunnel size. This also results in the signs of flow speed being different at different heights on a given tunnel.

Lukas' geology lessons:

Beautiful cave holes:

Views from the cave:



Cave forms:

Newspaper stuck in mud:

The western, original cave entrance:

This article has also been published at TGR. Tämä artikkeli löytyy myös suomeksi Relaasta. All caving articles and videos can be found from the site! Photos (c) 2018 by Jari Arkko. All rights reserved.

Saturday, August 25, 2018

Black Snow. Again.

I was again at Hintertux for summer skiing, at the low point of the yearly snow cycle. The glaciers were dark... black even.

See below for a picture of one of the slopes. Notice the skier on the left.

Grass hills in the valley, however, were wonderfully green:

This blog is also available at the TGR site. Tämä blogi löytyy myös suomeksi Relaasta. And more skiing videos and stories are always available at!

Photos and videos (c) 2018 by Jari Arkko. All rights reserved.


Had a nice swim in Austria's Attersee when driving past the area. Water temperature was just right, cooling down on a hot day.

Photos (c) 2018 by Jari Arkko. All rights reserved.

Wednesday, August 22, 2018

Langbathseen Swim

Had a nice swim today, up the road from Ebensee. At the Langbathseen lake. Very nice, clear, blue, greenish water, and a wide beach with plenty of room even on a hot day.

I also learned a new word, oligotrophic. It means a lake with not much organic nutrients. It makes for clear lakes, but less algae and even fish.

Photos (c) 2018 by Jari Arkko. All rights reserved.

Tuesday, August 21, 2018

Eurospeleo Photography Workshop

This week some of us Finnish cavers are attending Eurospelo in Austria. The first session for Jukka, Tor, me, and our Canadian friend Andrew turned out to be cave photography, learning to use backlight with Philippe Crochet and Annie Guiraud. Amazing stuff, very happy that we were able to join.

I'm also very surprised that results improve if you know what you are doing :-) Philippe and Annie certainly know; some of their work can be found at

Jukka practising the photos with Philippe's help:

Jukka, Philippe, and Andrew planning their shoot:

At the entrance of the cave, looking out:

Photographers at work:

Eurospeleo sign:

This article has also been published at TGR. Tämä artikkeli löytyy myös suomeksi Relaasta. Photos (c) 2018 by Jari Arkko. All rights reserved.

Saturday, August 11, 2018

Recycled Hamburg flak towers

During World War II, the Nazis built so called Flak Towers -- fortified air defence bunkers -- in three cities, Berlin, Vienna, and Hamburg. I had previously been in the Thumboldthain tower in Berlin. Now I was able to visit two similar bunkers in Hamburg.

Whereas the Berlin bunker has been partially blown up, the Hamburg bunkers are in much better condition. One acts as a music school, media business park, and hosts shops.

The other one has was demolished internally with six of the eight floors collapsed, but has since then been renovated. This bunker acts today as a solar cell platform and buffer storage for renewable energy. Two million litres of water are used to store energy generated on the site, drawn from the solar cells, or waste heat from nearby industries. At the top the <vju> Café opens up for guests three days a week to look at the views and enjoy coffee.

The first bunker, Heiligengeistfeld Flak Tower is at the Heiligengeistfeld park in the center of Hamburg (N 53.55667 E 9.97036). The second bunker, the Energy Bunker is at Wilhelmsburg in the suburbs (N 53.50999, 9.98941). More information about the flak towers in general can be found from the wikipedia page.

I have mixed feelings about the bunkers. On one hand, they were a part of the German war machine, and the horrors of war are still all too present in their dark insides. But on the other hand, these bunkers are also interesting structures from an engineer perspective, and their current use is in stark contrast to the evil war times: teaching people about music or providing alternate energy sources.

There were beautiful concrete cuts... imagine having to slice through several meters of concrete to make a new door!

I loved the painted concrete walls:

And I also loved this graffiti:

There were also claustrophobic concrete hallways:

I wanted to get to the top of both bunkers, but did not manage to get to the roof bar on the Heiligengeistfeld bunker; the Terrace Hill bar was closed even if it was supposed to be open... but otherwise I was able to move inside that bunker, through the shops and offices. The bar would have been nice though, with palm trees on top of cold, grey concrete:

When visiting the Energy Bunker it was hit by a thunderstorm, rain poured down, and I was worried that I would not be able to leave without getting my backpack and computer wet. But the storm was just a front... it passed by:

More pictures from the Heiligengeistfeld tower:


More pictures from the Energy bunker:

At the roof they had an advertisement for small sleeping tents/cabins:

Other pictures from Hamburg:

This tower welcomed me on the way to the bunkers:

This article has also been published at TGR. Tämä artikkeli löytyy myös suomeksi Relaasta. Photos (c) 2018 by Jari Arkko. All rights reserved.

Wednesday, August 8, 2018

New skis for the summer!

Skis for the summer acquired, from Ski-service in Pitäjänmäki. They opened the shop for me :-)

The new skis are Völkls, 100mm wide. A bit wider than I had before, and pretty high speed/less turning radius than I had before. Lets see if I like them... at least they run very stably, based on experience so far :-)

Photos (c) 2018 by Jari Arkko.