Some general information
What is karst? They are limestone plateaus, characteristic of the Dinaric and transnational Alps - Slovenia, Croatia, Italy - from which relief formed by the double hydraulic and hydrochemical erosion of the rock stands out. This erosion has formed cavities, sinkholes and faults, especially under the earth's surface, which has allowed the development of an important network of underground waters and caves. The latter are home to a unique ecosystem of fauna and flora that never see the light of day. A large part of this stunning landscape was classified as a biosphere reserve by UNESCO in 2004.
In Slovenia, there are more than 20 caves open to the general public and about 50 with a more established audience. Of course, you need to equip yourself properly, as the humidity level is very high and the average temperature rarely exceeds 12°C.
The geographical distribution of the caves is quite wide in Slovenia, as 50 % of the country's soil is limestone. They are found mainly around the Kras region, west of Ljubljana, in the direction of neighbouring Istria.The complexity of the study of karst
The main research center, at the forefront of karstology worldwide, is located in Postojna. It was established in 1947 and is home to renowned scientists whose aim is to study karst phenomena that are still largely unknown. They publish in the internationally renowned journal Acta Carsologica. Their research focuses on the formation of underground water, the establishment of animal life underground, etc. In particular, they have managed to establish that half of the Slovenian population is supplied with karst water. Slovenian caves, most recently the Divaška cave, are also used as a training base for NASA astronauts, who test the delicate living conditions in darkness, silence and permanent humidity. Finally, a Karst museum was opened in Postojna in 1992 and contributes greatly to the collective effort to popularize science.
Caving, a national sport
There are more than fifty caving associations and clubs across the country, united in the form of a federation. They carry out several types of activities: exploration, observation, guided tour expeditions, educational activities for school audiences, supervision of the safety of caves open to the general public, assistance and rescue of people at risk. They also issue a compulsory permit for the confirmed practice of speleology and the exploration of certain caves which require the possession of this document.
A little-known discipline: biospeology
It is the study of the way of life of cave dwelling organisms. Researchers are trying to answer such fundamental questions as: How did they get here? How did they adapt to this special underground environment? How do they feed on a daily basis? Generally speaking, to simplify things, there are three types of cave animals. The first are the troglobies that have been able to fully adapt to life underground such as certain crustaceans, fish or amphibians like the eel proteus. The second category is called troglophiles, which mainly use the underground world as a living space. This is the case of certain birds such as the cave guacharo or insects such as spiders. Finally, trogloxenes partly use the cave for comfort - hibernation for bears or bats, for example - or as a temporary refuge for rodents in particular.
Large-scale underground tourism: the examples of Škocjan and Postojna
Located in the municipality of Divača, close to the Italian border, the Škocjan Caves
form the largest underground wetland in the world. The impressive flow of the Reka River breaks the silence for a few minutes. The ecosystem is particularly well preserved and it is not unusual to come across a few species of bats! The discovery of the dead lake (Mrtvo Jezero) encourages meditation. We think back to the words of Sigmund Freud during his visit in 1898: "If Dante had been able to see something like this, he would not have needed to use his imagination much to describe the Underworld. "The complex was declared a UNESCO World Heritage Site in 1986 and 100,000 visitors flock to it every year. is impressive in its scale and size, reaching 24 km of underground galleries. This almost baroque complex attracts an exceptional fauna: the famous eel proteus, the beetle, disconcerting looking crustaceans and numerous spiders. However, the flip side of the coin is obviously the massification of tourism in the most visited cave in Europe - 40 million visitors since its discovery and more than 500,000 a year: the ecosystem is disrupted and tends to flee contact with tourists. Not classified by Unesco, this cave has managed to impose its model in terms of underground tourism by designing a small train that allows you to weave your way through these dark caverns - it has been in existence since 1872! It has been in existence since 1872! - but also provides a lighting system that gives a certain sparkle to these grandiose landscapes. Cave tourism is an ancient practice, inspired by discoverers and writers such as Édouard-Alfred Martel - founder of contemporary speleology and a visitor to Postojna - or Jules Verne. It allowed an early protection of these fragile places which has resulted in a good state of conservation until now. The massification of tourism, especially in Postojna, now poses new challenges in this area.Other caves to discover
It is difficult to be exhaustive in this field as Slovenia is full of caves, each more impressive than the other. We will gladly stop in the Križna cave, south of Postojna, which offers a prodigious decor of stalactites and stalagmites as well as views of several underground lakes. Only the dry parts can be visited on foot, the rest of the exploration is done by boat. A few kilometers away, we find the Planina cave
, which has the particularity of housing one of the largest confluences of underground rivers in Europe. The aquatic spectacle is of great beauty. Further west, in the direction of Trieste, is the Divaška Cave, discovered in 1884. Its limestone deposits that have left their indelible mark are worth a look. Local legend has it that Sigmund Freud visited it. The cave of Vilenica, nearby, is known to be the oldest visitable cave in Europe, since the 17th century. Finally, further away, in the center of the country on the Velenje-Celje axis, is the Hell Cave, where you will marvel at the highest underground waterfall in Slovenia.
