Green Karst: A Treasury of Slovenian Gems

By , 19 Feb 2018, 10:25 AM Travel
Križna cave Križna cave Wikimedia Commons, Public domain

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Castles, caves and the birth of karstology, the science of karst. 

February 19, 2018

If you’ve ever taken the A1 highway from Ljubljana to the coast you might have noticed an unusual density of brown exit signs. Brown is the colour depicting a cultural monument, and between the Unec Exit, Postojna and Divača, in about half-an-hour drive, you can see quite a few of these:

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Unec exit for Cerknica lake, Rakov Škocjan and Snežnik castle



Postojna exit for Postojna cave and Predjama castle


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Divača Exit for Škocjan caves and Lipica stud farm


All of these exits lead to at least one of the karst phenomena, the caves. However, apart from Divača, and even Divača is only considered partially karst, these places don’t really belong to the area known as classic karst, which is a land of bare stone, low bushes and pines, vineyards and a strong wind called burja. Instead, the area is known for its rich flora and fauna, hence the name green karst.

Let us begin with the first of the exits above, Unec, the one leading to Cerknica Lake, or more generally speaking, Notranjska regional park. Well-known sites to visit once you have left the A1 highway start with Rakov Škocjan, a great hiking place that used to be cave, but after the ceiling collapsed is now a valley. Going further there is Lake Cerknica, if you pass it, you can visit Snežnik castle  and finally, by the Croatian border there is Mount Snežnik, which serves as the source of the waters that carved out the major part of the green karst underworld.

If we go backwards by tracing the water flows that shaped the Park Notranjska phenomena, starting at Snežnik, we see how the water repeatedly disappears and re-emerges in the karst fields of gradually decreasing altitudes, until it finally re-emerges in Ljubljana basin (in Vrhnika) as the River Ljubljanica, the landmark of the Slovenian capital. To put it differently, Ljubljanica is composed of the rivers Pivka, responsible for carving out the Postojna cave, and Unica, responsible for Križna cave and the Notranjska underworld, which, when full, creates the disappearing Lake Cerknica.

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The path of the Snežnik waters from Babno polje to Ljubljana basin. Screenshot of a YouTube video

The rains in spring and fall bring large amounts of water to the area, and when the underground is filled the remaining water forms lakes on the surface. One of the largest such lakes is the aforementioned Lake Cerknica. The area has an amazing amount of biodiversity, and about half of all European bird species, if we use birds as an example, can be found in this one place. For more information on where, when and how to visit, click here


Lake Cerknica: fish heaven and hell

The park is also the location of one of Slovenia’s most exciting caves, Cave Križna (Križna jama). Once home to cave bears, which left some of their remains at least 24,000 years ago, when they became extinct, Cave Križna may be one of the prettiest caves in the country, mostly due to the many lakes (45 all together), which also make it less accessible to the mainstream tourism. If you’d like to visit this beauty, click here for more information.


For this and more photos of Križna Cave click here.

If you’d like to visit something that takes less effort and organisation, head back to the A1 highway, drive about 10 more minutes towards the littoral, and take the next exit for Postojna. This famous cave, which is celebrating its 200th anniversary of tourism this year, is readily accessible from the street. Due to its vast size the cave can receive large numbers of visitors at once, and therefore no reservations are needed. You just show up, buy the ticket (25 EUR per person) and wait for a train to take you in. The guided tour includes a train ride, and a walk through the large halls of the cave on the paved paths and stairs. The cave is well lit, and all you’ll need is clothing appropriate for the constant temperature of 9 degrees Celsius, the same temperature one finds in the majority of the Slovenian wine cellars. Below is a video of the train ride into the cave.

The proximity of various world-famous phenomena in the area of Slovenian green karst is also the reason why it was here that karstology was established as a special field of science. Furthermore, the geographic and historical conditions dictated that the first explorations of the underground life also began in the area of Postojna. The first troglobiont (a cave dwelling organism) was scientifically described in 1758, and this was no other than the human fish (človeška ribica) with its scientific name Proteus anguinus, which was then followed by a bug named Leptodirus hochenwartii in 1832, and only then did the exploration of such species continue elsewhere. Today, we know that with about 200 land species, and another 200 water ones, Slovenia has one of the richest cave fauna in the world. Unfortunately, this also seems to attract poachers from all over the world, as only in the last year bug traps were discovered at several of the more exposed caves of the green karst, with some of the most endangered species already caught and preserved in them. The poachers seem to set traps filled with a preservative, then leave for several months and return to collect their prey. Such criminal activity, if spotted, should be reported immediately to the nearest park keeping association, or if that is not possible then to the police.

Just further down the same road that brought you to Postojna Cave you can continue your journey to Predjama and its picturesque medieval castle, which was originally built into the cave on the side of a cliff, with another cave that hides in a cliff wall below the castle. The castle has a naturally formed secret vertical passage to the top of the cliff, and therefore presents an excellent spot for such a fortress in case of a siege, and many interesting stories, both true and legendary, are attached to this structure. Details for visitors can be found here.

Predjama by Jackie Chan

To visit the most famous of the Slovenian caves, that is Škocjan caves, listed under the world heritage sites of UNESCO since 1986, you will have to get back to the A1 highway and drive half an hour further west to cross from the green karst into the classic karst and exit at Divača. From there you can either opt to turn south for the caves, or west to the Lipica stud farm, the stables that used to supply the Vienna court with white horses known as Lipizzaner.

The vast caves of Škocjan are quite dark on the inside, hence the lack of footage.

The geographic and historic circumstances that allowed for the first exploration of the cave life in the area of Postojna, as noted above, are found in the crossroads of some major historic routes, connecting Central Europe with Eastern Europe, and both with the Adriatic sea. This is the place where the Pannonian basin comes closest to the Mediterranean, and has therefore always been the corridor of large movements of goods, peoples and armies. Alongside these routes towns were formed that lived from the crafts and services needed to support thousands of passing carts and their passengers: workshops, restaurants, stables and inns. This form of economic activity as a whole, from moving carts to their support industries, is known as furmanstvo, a tradition still celebrated in the region with an annual holiday and a procession of horses, carts, and various associated items and practices.

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Screenshot of a YouTube video

This is why the area is also full of prehistoric remains, Roman settlements, underground fortresses, bunkers and walls, medieval castles and the ruins of the fortified anti-Turkish camps (tabor) that people built during the Turkish raids, usually around local churches. One of the best-preserved specimens of a tabor is a small Holy Trinity church at Hrastovlje, with a preserved late medieval Dance Macabre fresco.

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Hrastovlje tabor with Holly Trinity Church in the centre, Wikimedia Commons, CC generic 2.5, Ed88

Several hundreds of years of military history in the area can be seen summarised in the permanent collection of the Regio Carsica Militaris Museum in Pivka (exit Postojna).


Screenshot of a YouTube video

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