It is the only naturally preserved tourist cave in Slovenia, so it contains no strong lighting and concrete pathways. Before entering, visitors receive rubber boots and a portable, rechargeable flashlight. Extremely slow growing sinter barriers between lakes (up to 0.1 mm per year) and their fragility present the main obstacle for visitors, which prevents mass tourism and causes a restriction to the daily number of tourist, who can visit the water part of the cave, which is limited to four people.
The main guideline while visiting the cave is to limit consequences of tourism on the sinter barriers and to the level of natural self-restoration of the cave – which places it among the best preserved tourist caves in Slovenia. The maximum credit for that belongs to certain members of the Assotiation of Križna cave lovers, who dedicated much of their time to the cave, and handed out their experience to the younger generations.
Among karst caves, Križna cave is known to the world due to it’s underground lakes.
Since the elimination of carbonate from the water at rapids is more than ten times faster compared to lake water, that leads to formation of sinter dams, which appear on spots, where rapids are located and caused lakes up to 7 meters in depth.
There are 22 lakes in the cave,which can be crossed by a boat, but if we also count in the smaller lakes of Blatnikov rov, the number rises to 45.
Each visit includes a boat tour. If you decide to attend a short, 1 hour tour, you cross a single – the first – lake. If you choose a longer, 3.5-4 hour tour, the path takes you across 13 lakes.
The longest possible, alternative tour, takes you over 20 lakes. During the tour the cave guide takes care of moving the boat over sinter barriers.
It is an active water cave with sinter dams, lakes and flowing water, which creates different rock forms, such as facets, grooves and ceiling pockets,… The water stream in the cave appears from beneath rockfalls at it’s eastern part. At low and medium water level there is percolating water, but at high water level, there is also the presence of disapearing streams of Bloke plateau (Bloška planota, Farovščica).
Water in the cave repeatedly disappears into a siphon, but resurfaces and finally leaves the cave in Kittlow wells (Kittlovih breznih), resurfaces in Križna cave 2, and once again disapears in it’s western end and once again appears in the spring of Šteberščica on Cerknica field.
Different animal species
Despite oligotrophicity, which means a small amount of nutrients in the water, the cave is rich in terms of underground fauna. Until year 2000, they discovered 45 underground animal species, which ranks the cave 4th in the world by it’s diversity. Both water and surface animals are frequent: dripstone amphipods (Niphargus stygius), blind amphipods (Niphargus orcinus), cave hedgehog (Monolistra racovitzae), 6 species of tiny snails (3 of them endemic), cave Isopoda (Titanethes albus), cave spider (melted taenaria) drobnovratnik (Leptodirus hochenwartii), cave worm (Pelodrilus Buresch).
Also frequent are periodical cave animals like Lesser horseshoe bats (Together with the Cave Novi križ the second largest wintering spot for bats in Slovenia). Two species actually gained their name after the Križna cave (bug križnojamski brezokec, križnojamska belgrandiela).
Large blind amphipods
A location of cave bear
Part of the skeleton (skull) can be seen during all Križna cave tours. If you want to see a larger amount of cave bear remains you can decide to attend an alternative tour of Bear tunnel (Medvedji rov).
The bones of a cave bear (Ursus spelaeus) were firstly noticed in 1847 by Aleksander Skofiz, who reported it to the curator od Museum of Ljubljana Henriku Freyerju. Excavation was started in 1878 by Ferdinand von Hochstetter. In just four days more than 2000 remains were discovered, which makes the place the richest in remains in this part of Europe. He assembled two full skeletons, which were then sent to Vienna’s Natural History Museum.
In addition to the amount of bones, their size also stands out – the largest found skull in cave Križna is 56 cm long. There are many different opinions about the actual age of the bones – they are considered to be between 45.000 and 146.000 years old. Due to the large amount of the bones it is possible, that the cave was a home for the bears for tens of thousands of years. That is also shown by many bear marks on the rocky walls.
First known visitors were from metallic periods of time. Archaeoligists discovered a large amount of old pottery, the oldest of which are almost 5 thousand years old (from the time of Eneolithic, about 2800 B. C.). People didn’t actually live in the cave, but used it as a hideout.
The beginnings of tourism are strongly connected to exploration and research – they can often also be equated. First proofs of cave »visits« were made in 1557. In the following centuries the cave was constantly, but rarely visited. The most looked at were the entry areas – most of the people didn’t even reach the first lake. With the discovery of cave bear remains the amount of tourism rose.