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Eyes of God in Prohodna, Bulgaria
Eyes of God in Prohodna / Boris Jordanov, Flickr / CC BY 2.0

WorldBlue  In short

There are many wonders in the world – see yourselves in this website! But sometimes even Wondermondo is surprised – does it really exist? One of such surprises is Prohodna – a unique cave in Bulgaria.

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GPS coordinates
43.1758 N 24.0730 E
Location, address
Europe, Bulgaria, Lovech Province, cave at the southern bank of the Iskar Gorge near Karlukovo
Caves, Rock formations, Natural arches
Name in Bulgarian
Проходна (Passage)
262 m

Map of the site

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WorldYellow In detail

Wonders of Karlukovo Gorge

Bulgaria has got many beautiful places but one of the most impressive ones is the enormous Iskar Gorge – a picturesque, long valley crossing the Stara Planina mountains from Sofia towards the Danube.

One of the entrances in Prohodna, Bulgaria
One of the entrances in Prohodna / MrPanyGoff, Wikimedia Commons / CC BY-SA 3.0.

Most interesting and impressive is the tributary of Iskar Gorge – Karlukovo Gorge. Here one can see many impressive limestone formations – tall walls, arches, giant caves – all rather resembling some far away exotic land and not the European Bulgaria.

In Karlukovo Gorge and near it are known more than 280 caves, including such wonder as the 4.5 km long Temnata Dupka with a multitude of important early human finds.

But by far the best known local wonder is Prohodna – "Passage".

Passage for giants

Very often caves are narrow – one should struggle to get through them. But this is not the case in Prohodna, not at all. Prohodna is comparable to a giant, 262 m long tunnel of gargantuan size. The so-called Small Entrance (Малкият) is 35 m high but the Big Entrance (Големият) is 42.5 – 45 m high – the largest cave entrance in Bulgaria. The giant size of the cave makes it suitable for bungee jumping – with a 56 m high jump!

Prohodna and the Eyes of God, Bulgaria
Prohodna and the Eyes of God / Vassia Atanassova, Wikimedia Commons / public domain.

Present-day Prohodna is just a part of the once larger cave. The thin upper layer over the cave is gradually collapsing and sometimes in the future there will remain only a steep gorge instead of the cave.

Floor of this giant cave is comparatively plain and in the past – in Neolithic – Chalcolithic ages it has been inhabited by humans.


Prohodna is a very impressive cave but by far the most impressive feature here is two enormous holes of similar size in its ceiling, which resemble giant eyes.

Reflection of "eyes" in Prohodna, Bulgaria
Reflection of "eyes" in Prohodna / Vassia Atanassova, Wikimedia Commons / public domain.

These openings are known as Oknata (Windows) or the Eyes of God – but sometimes named also the Eyes of the Devil. Each of these holes is some 20 m long and up to 6 – 8 m wide.

These giant eye-shaped holes create some eerie effects. When the Sun shines through the holes and one stands outside the cave, the enormous reflections of the sunshine "eyes" inside the dark cave look as if an unknown creature of giant size is hiding there. When it rains – the mysterious eyes are weeping, as if nature itself is sad. On clear nights the stars can be seen through these eyes.

In spring equinox the Sun shines in through Oknata and illuminates a small waterbody. It is possible that this effect was used in the rituals of prehistoric people living in this area.

The most amazing aspect is the exact shape and similarity of both holes – they look exactly like eyes. Nature sometimes creates true, even unbelievable wonders.

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Belogradchik fortress and cliffs, Bulgaria
Belogradchik fortress and cliffs / Klearchos Kapoutsis, Flickr. CC BY 2.0

Wonders of Bulgaria

Bulgaria is very rich with wonders indeed: both natural and man-made and quite a few are without analogs in the world. Some of the most interesting ones are diverse landmarks that are left by the Thracian culture, several very impressive Christian monasteries, and a wealth of very interesting rock formations.

Manjang Cave, South Korea
Manjang Cave / Korea.Net, Flickr / CC BY-SA 2.0


Every year there are reported exciting discoveries of new caves and discoveries of new qualities such as cave paintings in the ones known before. But there still is a feeling that our knowledge covers just a small part of all these monuments of nature.

Though, those which are known to us, offer a surprising diversity of unusual features and impressive sights.

The Wave, Arizona
The Wave / Greg Mote, / CC BY 2.0

Rock formations

This diverse and extremely interesting category of natural landmarks includes such landmarks as natural arches, balancing rocks, ravines, rock spires, and others. Many natural stone “sculptures” seem to defy gravity and other natural laws – but they exist!

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Great Caves of the World

Caves are found on every continent. The United States is home to the world’s longest cave system, the Mammoth Cave in Kentucky, and to the world’s most popular tourist cave, New Mexico’s Carlsbad Caverns. Great Caves of the World takes readers to these and 25 other astonishing and challenging caves across the globe.


Despite its European location, Bulgaria is a surprisingly undiscovered country rich in natural resources, history, and culture. This lavishly illustrated DK Eyewitness Travel Guide is all you need to cover everything from Bulgaria’s capital, Sofia, to the ancient countryside villages of Koprivshtitsa and Veliko Turnovo.

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