Loaner car this weekend because they are trying to fix the ventilation on the Volvo. It already broke earlier but a working fan is becoming necessary now in the humid autumn. The word is that the adjusting switch is broken and there are no spare parts. Fortunately some old tractors may have parts that can be reused. Seems appropriate.
The ventilation problem was reported here earlier.
More car stories in the Planetskier blog series at Blogspot. The photos and text (c) 2025 by Jari Arkko.
Snow in Madrid??? I didn't believe it was possible, so I wasn't prepared. I should have had faith... of course there's snow. There always has been and always will be. Everywhere.
The IETF is running this week in Madrid. There’s been two hot topics: First, agents, crawlers and bots. They are as much as 30-50% of Internet traffic, but what are the policy controls for crawlers to access information, and do they have to keep polling unchanged content? Or should bots be authenticated? And should the IETF define AI agent to agent protocols, one of the most popular topics in the industry right now?
And second, people have been talking about how cold the meeting rooms are, the well known people-in-shorts-and-T-shirts-and-AC -problem. I don’t know, last night I found even cooler rooms from the Madrid Snozone.
Their home page is here.
Video:
Photos:
I also did some other interesting things in Madrid, went swimming in my hotel, for instance. And caving.
Read the full Planetskier series at planetskier.net, or all blog articles from Blogspot, TGR. For more sauna and swimming stories, check out planetswimmer.com and saunablogger.cool websites. Photos and text (c) 2025 by Jari Arkko.
Flying out of Madrid now after a very nice meeting, but not before hiking to the Cueve de Malvecino cave, did a 3D scan of it. This was in the Los Cerros park, east of the city. A hot hike, despite going there in the evening.
Cueva de Malvecino is a cave in the Alcalá de Henares / Parque Los Cerros park, east of Madrid. The cave is located in coordinates N 40.481448 W 3.343662. It is a bit unclear, but the caves appears to be man-made during the
There's also another cave nearby, but I didn't visit it. It is called the Cueve de los Gigantones, or También del Champiñón (mushroom cave) both due to the shape of the round room it has but also because it has been a place where mushrooms were grown. This cave has more built structure inside, brick walls etc., though they are in quite a crumbled state.
More information about the caves in this area here, here, and here. The caves are protected and should not be damaged or trashed, see this link. The coordinates to the Los Gigantones cave are these N 40.482949 W 3.332810.
I also scanned the Cueva de Malvecino. The resulting 3D model can be downloaded here in GLB format and here in Blender format, and rotated on your browser screen here (reduced resolution). A screenshot of the full model is below:
I also took the model and produced a map of the cave using my Cave Outliner software. The high-resolution PDF of the map is here, but a picture of the plan view is shown below:
Photos:
See also my other explorations in Madrid, such as skiing in the Snozone indoor ski hall.
Read the full Planetskier series at planetskier.net, urban exploration stories from theurbanexplorer.net, and other underground stories from planetcaver.net, or all blog articles from Blogspot, TGR. Photos and text (c) 2025 by Jari Arkko, except where otherwise indicated. All rights reserved.
I had another mini-vacation. Working for a long day, I decided to take off from the office and drive to Somero, an hour away to swim at the Loiske, the Somero swimming hall. It was quite a nice visit! They've built a new swimming hall to replace the one from 1970s, and the late evening visit made the hall almost empty... several lanes free just for me.
There's a 25 meter pool, a therapy pool, a waterslide, and a kiddie pool. In the washing rooms and sauna side they have two saunas (for both men and women), same type of Finnish saunas, no steam rooms that I could fine. But I prefer the Finnish saunas anyway.
Funnily enough, they have all the Somero services concentrated on the same place: swimming hall, school, library, the vet, etc.
The homepage of the hall is here. Some more information about the history of the hall project here.
More photos:
My previous mini-vacation was nearby in Forssa. Read the article here.
For more sauna and swimming stories, check out planetswimmer.com and saunablogger.cool websites! And of course the Planetcaver, and Planetskier blogs for other stories in Blogspot and TGR! The photos and text (c) 2025 by Jari Arkko. All rights reserved. No photos of sauna or beachgoers were taken. Pool photos are from by Somero's city, all rights held by them.
Yesterday I sailed to a company event on my friends boat. The views going there in the morning and coming back in the night were wonderful. We also tested a secret sauna island far out south of Espoo.
More information about the secret sauna island here, here, and here.
Sailing:
I have of course done this before with the same people... like last year :-) (article).
Also, who rides a horse on the sea??? And isn't the bottom muddy???
Author:
For more sauna and swimming stories, check out planetswimmer.com and saunablogger.cool websites! And of course the Planetcaver, and Planetskier blogs for other stories in Blogspot and TGR! The photos and text (c) 2025 by Jari Arkko. All rights reserved. No photos of sauna or beachgoers were taken.
The Krka National Park is one of the most popular parks in Croatia. It runs along the river Krka, and is reachable by about an hour's drive from Split or Zadar. The park is centered around the river and lakes on it, with incredibly beautiful gorges and waterfalls. There are many cruises, excursions, restaurants, one beach, and ... a large number of caves :-) I visited the main tourist-accessible cave, Ozidana Pecina along with some smaller caves in the area.
The park is large, but I focused on the most rugged section around the Roški Slap area. This area has multiple waterfalls, beautiful lakes, and a spectacular mixture of green wetlands through which the river flows. Roški Slap is in a deep gorge. At the bottom there are tourist information facilities, restaurants, and the park's only beach. It was a wonderful experience to dip in the rare non-salty water in Croatia :-) Particularly with a view of the waterfalls.
The nearest village to Roški Slap is Bogatić.
1. Ozidana Pecina cave
Let's focus first on Ozidana Pecina, the curated show cave in the park. This cave is well researched and documented. It is 59 meters long, a metro-sized tunnel straight into the rock in the middle of the cliff face of the gorge. It makes one turn within the tunnel, but is otherwise relatively straight. There are, however, several chimney features rising from the roof towards higher. But none of these chimneys appear to push through to the top of the cliff, or allow any kind of exit. How were they created? Perhaps there's some smaller water passages that allowed these to form.
The cave has been a human dwelling from around the Neolithic period, from approximately 6000 BC to about 1500 BC. Pottery, knives, etc. has been found in excavations on the site.
The coordinates for the Ozidana Pecina are N 43.907773 E 15.980609. The cave is on the path from the Bogatić Miljevački parking lot to the gorge, about 1/3 of the way from the parking lot.
I scanned the cave using my iPhone's lidar sensor and the Polycam app, and processed the resulting 3D models using Cave Outliner to get a map. Here are the 3D model links (GLB, Blender), a rotatable model for your browser, and the high-resolution PDF map. And this is what the model and the map look like:
Interestingly, if I compare this map to the one in a book about the Krka caves, it has this:
Pretty close, no? Or maybe my map is even more accurate than the one in the book, at least in the horizontal plane. I was unable to climb to the chimneys, which the other cave researchers probably were able to.
Photos:
More information about this cave can be found here, here, and here.
But I also visited a number of smaller caves along the hiking paths in the gorge. These don't have official names, but I named them according to what they looked like or where they were located. These caves are:
2. A-Frame cave
This is cave is at the bottom of the stairs that descend the path from the Bogatić Miljevački parking lot to the gorge. It is also on the educational hiking trail "Necklaces", where the two trails meet.
This cave forms an A-shape tunnel of about 14 meters, and has some weird ball-shaped wall forms inside.
The coordinates are N 43.907712 E 15.978869.
I scanned the cave, here are the 3D model links (GLB, Blender), a rotatable model for your browser, and the high-resolution PDF map. And this is what the map and the model look like:
Photos:
3. High shelter cave
The Necklaces trail has a footbridge over the Krka river. On the west side of the river is the A-Frame cave and the path up to Bogatić Miljevački parking lot. On the east side of the river right in front of the footbridge is a cliff with a high-up shelter covering the lower parts of the cliff. On the left side of the shelter there's a smaller, proper shelter cave that is just a 1.5-3 meters high and maybe ten meters deep.
The coordinates are N 43.908684 E 15.977146.
Photos:
4. Shelter cave by the raised path
The Necklaces trail makes a loop, crossing the river in the north with a footbridge, and a car bridge in the south. On the west side roughly in the middle between the two bridges lies two caves. The first one when coming from the north is what I called the shelter cave by the raised path. It is indeed right next to the wooden foot path.
The cave is a shelter cave, going 9.5 meters deep into the cliff. It is nicely formed and easy to access.
The coordinates are N 43.906810 E 15.975584.
I scanned the cave, here are the 3D model links (GLB, Blender), a rotatable model for your browser, and the high-resolution PDF map. And this is what the map and the model look like:
Photos:
5. Shelter cave behind bushes
The next cave on the Necklaces trail is what I called the shelter cave behind the bushes. It is just a few meters further south from the shelter cave by the raised path, but behind some bushes so not so easy to spot.
The cave is also a bit higher, maybe 2 meters from the ground, so you have to climb the easy rock underneath it to reach the actual cave.
It is a very nicely shaped, oval-formed cave, 8.5 meters into the cliff.
The coordinates are N 43.906758 E 15.975517.
I scanned the cave, here are the 3D model links (GLB, Blender), a rotatable model for your browser, and the high-resolution PDF map. And this is what the map and the model look like:
Photos:
6. The beach
The beach in Roški Slap was nice, as discussed earlier. It is in coordinates N 43.902101 E 15.975836, next to the restaurants, near the information desk in the gorge, etc.
Photos:
You need to buy timed tickets to visit the Krka National Park. You can get them here. More information from the park from their webpage or Wikipedia. I accessed Ozidana Pecina and the areas further down in the gorge from the upper parking lot at Bogatić Miljevački, here. It is an easy drive and Ozidana is near. The parking lots in the gorge itself near the Roški Slap waterfall are tiny and not recommended during the summer. And if you walk down to the gorge from the upper parking lot it is an easy walk, but in the heat of the summer walking up can be a challenge; I took the bus up. The bus runs every hour.
More Krka views:
Read the urban exploration stories from theurbanexplorer.net, and other underground stories from planetcaver.net, or all blog articles from Blogspot. For more sauna and swimming stories, check out planetswimmer.com and saunablogger.cool websites! And of course from the planetskier.net. Photos and text (c) 2025 by Jari Arkko. All rights reserved. No photos of beachgoers were taken.
