Sunday, June 16, 2024

Bosnian Pyramid of the Sun

I visited the Bosnian Pyramid of the Sun, as well as the Ravne tunnels few kilometers away. The pyramid is remarkably pyramid-looking green mountain and the tunnels are .. well, more about that later. Both are in the small town of Visoko, 35 kilometers outside Sarajevo.  The claim is that the pyramid is a concrete-covered man-made structure built by an ancient civilization 29 000 years ago. And that the tunnels were also man-made network leading under the pyramids, and only later filled in. And that there are health benefits to all of this. Long story short: lots of pseudoscience, but of course a nice mountain to visit. And it is always pleasant to be wet, dark underground tunnels. Even if the the support beams are rotting...

Here's a view of the "concrete cover" in the pyramid:

The "cover" is only visible in a few places, however, as the mountain is generally entirely covered by grass and trees. To my untrained eye it wasn't clear to my the "concrete" would be actually concrete -- some of it looks like regular stone, some looks like conglomerate rock found in many places.

A view of the pyramid from further away is shown below. The photo is taken from the town center if Visoko, at the very nice hotel Vema where you can ask for "pyramid view" rooms :-)

The main clue to all these claims being pseudoscience was when the tour guide said that it was shown water crystals are damaged by listening to heavy metal music. Clearly, heavy metal can only be good for everything, including water crystals :-)

For more information, look at the Wikipedia page for a critical evaluation of the claims about the pyramid. The organization pushing for the claims is Bosnian Pyramid of the Sun Foundation (home page).

They sell all kinds of interesting gadgets and materials in their shop at the Ravne site. An ionisator for 100€, a book in which their lead researcher, Semir Osmanagić, chats about the pyramid with ChatGPT, and so on:

But let's look at the claims more carefully:

Claim 1:

The pyramid is a man-made structure.

Evidence: Quoting Wikipedia's summary [1]: Direct study of the site by geologists, archaeologists, and other scientists has demonstrated that the hills are natural formations known as flatirons,[ and that there is no evidence that they were shaped by human construction. And quoting Stephan Coric from Bohannon's article in Science (2006): "The stone slabs are nothing more than fractured chunks of sediment called breccia" [2].

Claim 2:

The Ravne tunnels are man-made. 

Evidence: one of the basis of the claims that they are man-made rests on finding "dry wall" stone structures in the tunnels. These are rocks laid on top of each other by humans, with little sand or other material in between. Here's a photo, as well as a book excerpt from Osmanagić:

However, this is far from convincing. Any openings (man-made or natural) under ground are prone to water flows, and rivers can wash rocks clean by transporting small material away. Later new floods may bring new material and, e.g., cover layers of rock by mud or silt as shown in the book picture. We see these in natural caves all the time. Or, perhaps these layers of dirt and rock were on the surface at the time rocks moved around with the force of water. 

And it is undisputed that the foundation dug out the tunnels. They took material out, and built the wooden supports to hold the the rest of the material above the tunnels up. Did they just dug in plain natural hill, perhaps leveraging some naturally occurring channels of differing materials inside? 

Or, quoting Anthony Harding speaking in [2], "If these were made by humans without establishing their age, I would just assume they are part of an old mine". And Harding's verdict was "Its just a hill".

Claim 3:


Schumann Resonance is real phenomenon. The question though is if it has a health impact. A Japanese research team concluded that "neither subjective health nor depression was significantly associated with BPR-SR (blood pressure reactivity to Schumann Resonance)" [3]

Claim 4:

This is based on Masaru Emoto's work on "water crystals" and the possibility that water would carry information. 

Evidence: Biochemist and Director of Microscopy at University College Cork William Reville wrote, "It is very unlikely that there is any reality behind Emoto's claims." [4,5]

Claim 5:

I was unable to find research articles, but the problems with this claimed scale are many, starting from that no one has published a definition or method for measuring it. As the Wikipedia article [6] puts it: "These are pseudoscientific concepts devoid of any experimental evidence.".


So no, there's no linkage with any of this to real things.

However, speaking personally, I still like to calm down and mediate in dark, wet underground places. There's something about the silence and darkness that soothes me :-)

So the tunnels *are* good for mediation:

Do pay attention though, I'm not entirely sure the tunnels are in great shape. They are excavated tunnels in a loose or conglomerate rock and sand. Cave-in is a real possibility, particularly when the support beams look like this:


[1] "Bosnian pyramid claims"- Wikipedia.

[2] Bohannon, John (22 September 2006). "Mad About Pyramids". Science. 313 (5794). AAAS: 1718–1720. doi:10.1126/science.313.5794.1718. PMID 16990525. S2CID 161209455.

[2] Mitsutake G, Otsuka K, Hayakawa M, Sekiguchi M, Cornélissen G, Halberg F. Does Schumann resonance affect our blood pressure? Biomed Pharmacother. 2005 Oct;59 Suppl 1(Suppl 1):S10-4. doi: 10.1016/s0753-3322(05)80003-4. PMID: 16275477; PMCID: PMC2656447.

[3] "Masaru Emoto". Wikipedia.

[4] Reville, William (February 17, 2011). "The pseudoscience of creating beautiful (or ugly) water". The Irish Times. Dublin. p. 14. ProQuest 851900025.

[5] "Scala Bovis". Wikipedia.

More photos from the tunnels

Read more urban exploration stories from, and other underground stories from Read the full Planetskier series at, or all blog articles from Blogspot or TGR. Photos and text (c) 2024 by Jari Arkko. All rights reserved. 

Saturday, June 15, 2024

Murvica Beach


I visited the Murvica beach after my exploration of the Zmajeva Pećina cave. on the south shores of the Brač island in Croatia. A welcome swim, not only for washing off the sweat of the climb, but also because it is such a nice, secluded beach and easy to swim at.

There's a small bar and pizzeria on the beach as well. 

Read more about Murvica here.

Here's a picture of the beach from high above:

For more sauna and swimming stories, check out and websites! And of course the Planetcaver, and Planetskier blogs for other stories in Blogspot and TGR! The photos and text (c) 2021 by Jari Arkko. All rights reserved. I never take recognisable photos of other saunagoers or swimmers. and try to visit at times where there is simply no one else around or the facility has been booked only for me.

Hermitage in a dragon cave: Zmajeva Pećina


Zmajeva Pećina, "Dragon's Cave" is a small hermitage on the south shores of the Brač island in Croatia. The cave is only 20 meters long, but is a fascinating visit, both because is such as fascinating view, high cave on a high hill, and also because my guide Zoran knows so much about the history of the place. This is a cave that houses a monastery. Or housed, it is in ruins. Very interesting!

More information can best be acquired by joining Zoran's guided tours, or from, Wikipedia, Brač  info, and this article.

I also recorded a 3D scan of the cave (but not to the top of the cave, my iPhone sensor did not carry that far). Below you can see a screenshot of the model and a map. You can also access the model on your browser, rotate it around, etc. here. And the map is available in PDF format here.

See also the article about Murvica Beach.

Read more urban exploration stories from, and other underground stories from Read the full Planetskier series at, or all blog articles from Blogspot or TGR. Photos, videos, and text (c) 2021 by Jari Arkko. All rights reserved.

Biševo's Blue Grotto

Biševo is a small island in the Adriatic Sea archipelago, in Croatia. It is just off the larger island Vis. Under the sea front cliffs of this island there's Modra špilja or the Blue Grotto. A cave in the limestone rock, lit inside entirely blue by sunlight filtering through the underwater entrance. This cave has been called the world's most beautiful cave. Obviously a category with a lot of competition and different criteria could be applied. But, I don't think the claim is outrageous. It is remarkable.

And no, you don't have to dive to get in. There's apparently a natural entrance from the top somewhere, but the tourist entrance is a tiny hole just barely above water, enough for a small boats to enter if everyone ducks their head entirely inside the boat. The tiny hole was man-made in 1884. The cave itself is only 24 meters long, but quite high, as well as deep under the sea.

The experience is magical! This really is a blue light moment, very odd feeling when one is used to dark and moldy caves :-) Much recommended.

The cave was made popular by Baron Eugene Ransonnet in 1884, when he wrote an article about it in the a newspaper in Vienna. He believed it topped Grotta Azzura, previously believed to be world's most beautiful cave.

Biševo island otherwise would be an interesting excursion place. There's been a monastery on the island from 1050, though it was later abandoned due to the danger of pirates. It is one of the outermost small islands in the archipelago, and only got electricity for instance in 1970. Inhabitants in the island live off fishing, including spreading their expertise much further than in the archipelago. A migrant from Biševo, Martin Bogdanovic, is said to be a founder of US fishing industry, for instance.

How to get to the Blue Grotto? There ferries and catamarans running from Split to Vis several times a day, tickets are 8.60€ one way on Jadrolinija. The ferries to Vis arrive on the town of Vis; there's a bus leaving right in front of the ferry to the small fishing village of Komiža (tickets 3€). The ride takes 20 minutes. From Komiža's harbor there are multiple water taxi services to Biševo and the Blue Cave, prices vary but expect to pay 50-100€. The boat trip will take half an hour on a fast boat, and the boat will wait for you while you get on a tiny boat to make the official cave visit. I can't remember the price of the tickets for these, but I think was in the order of 10€. Beware that there are also more complete tours, either from Split or Vis that are inclusive everything, but they are potentially also more expensive.

More information about the Blue Grotto can be found on the Wikipedia page and the show caves page. I can also recommend the excellent book, The Azure Sun: The Blue Grotto on the Island of Biševo by Joško Božanic. I can't find an online source to buy this book, but it should be on sale everywhere on Biševo and Vis. This book and Božanic has been the prime source of information in this blog article - thanks!

More information about Biševo can also be found from its Wikipedia page.

I did not realize this when visiting , but there's another cave on the Biševo island, the Medvidina Špilja (Monk Cave) as well. Now I have to visit again... And if you haven't been to the island of Vis, there's also many interesting bunkers (fancy a swim in an underground submarine base?) and caves (an article about the Queen's cave is pending... but there's also Tito's cave) there as well!

Entrance to the cave:


The underwater entrance to the cave, from the outside:

Komiža and the taxi to the grotto:

Read more urban exploration stories from, and other underground stories from Read the full Planetskier series at, or all blog articles from Blogspot or TGR. Photos and text (c) 2021-2024 by Jari Arkko. All rights reserved. 

Sunday, June 9, 2024

First mökki-swim in 2024... driving on a Jaguar

Too busy, and now without a car I have not been able to visit the summer cottage this year at all. Sigh. But now my car repair shop nicely loaned me a four-liter green '99 Jaguar for the weekend. Very nice! And a fun car to drive. And it was such a bliss to drop into the lake after visiting the sauna. The water was warmer than it probably has ever been on June 1st...

(But don't ask why the repair shop can afford such nice loaner cars... maybe the old Volvo repair business is picking up?)

More issues with Volvo: the previous breakdown was due to fuel pump relay. Now it is again the relay but on closer inspection the relay burns out due to the pump inside fuel tank drawing a lot of current. This sounds bad, even to me. All fixable (with some uncertainty factor) but the cost is again increased. I’m now definitely questioning my choices.

More about the Jaguar:

Volvo at the garage:

Cottage swim night and day:

Cottage food, halloumi burgers:

Cottage views:

For more sauna and swimming stories, check out and websites! More car stories in the Planetskier blog series at Blogspot. Read more urban exploration stories from, and other underground stories from Read the full Planetskier series at, or all blog articles from Blogspot or TGR. Photos and text (c) 2024 by Jari Arkko. All rights reserved.  I never photograph pools, beaches or saunas unless the facility is closed or empty.