Postojna Cave extended once again

Pivka Cave, the first siphon, the second siphon, an air pocket, the third siphon, Magdalena Cave! This is the cave explorers' historic dive and the recently discovered new connection within the Postojna Cave system described in a few words.


At the company Postojnska jama we are once again updating the map of the 24,120-metre-long cave system and marking the missing parts on the map of the subterranean course of the River Pivka to make it easier for everyone to understand where and how the cavers have again made the Postojna Cave system even longer following the waterways that are otherwise known only to the cave-dwelling olms.

"WOW… "

… was our initial reaction to the news that, after a two-hour swim, two cavers-divers, Igor Vrhovec (JKŽ Ljubljana caving society) and Sebastjan Gantar (JD Rakek caving society), emerged from River Pivka with the news of the discovery that we had been waiting for for 45 years. With the dive (and the measurements they carried out), the two divers connected – by means of a natural way – two caves of the Postojna Cave system, namely Pivka Cave and Magdalena Cave, which had previously been connected only through an artificial tunnel through the Black Cave. 


Cavers tried connecting the two caves (by means of a natural way) as early as 1972. They swam through two siphons, but failed to find a way onwards, hence the Zvezni Siphon (Connecting Siphon) way previously only 400 metres in length and there was a dead end marked on the map. Earlier this year, a team of explorers decided to give it another go and explore the passages that were marked on the map in 1973, with the aim of mapping them more accurately.


On 13 April, when conditions for a dive were perfect (in terms of visibility and the water level), the two divers dived into the Zvezni Siphon. Everything went smoothly, visibility was 3 metres (as far as caving goes this terms excellent) and the divers made their way along the course of the Pivka accompanied by olms. The divers were familiar with the first and the second siphons thanks to the map, but kept following the river and were then the first to break through an air pocket into the previously completely intact third siphon, which led them straight to Magdalena Cave. Getting out in Magdalena Cave made history as the official size and length of caves equals only the area that cavers have walked, swum, measured and mapped (official revisions to the map are in the works).


Previously, the Zvezni Siphon was a mere 382 metres in length, however, now – after the aforementioned dive – it is 422 metres in length and 17 metres in depth. This means that additional 40 metres have been added to the existing 24,120-metre-long Postojna Cave system. However, since this is not the only focus area of the team of explorers who work on connecting Postojna Cave and Planina Cave, and thus on extending the most famous cave system in Slovenia, new numbers and lengths are added elsewhere as well. After two years, the Postojna Cave system is thus longer by a total of 220 metres and its length will in the revised map now amount to 24,340 metres. That is, unless cave explorers surprise us with some new discoveries in the coming days.



The Postojna Cave system is a system of subterranean passages created and connected by the River Pivka. According to current data, the system is still officially 24,120 metres long and consists of 5 caves, the world-famous Postojna Cave being the largest among them. It is known that the River Pivka connects Planina Cave and Postojna Cave, however, since cave diving is a very difficult endeavour, the two caves are officially not yet connected. This complex task has been undertaken by a team of 20–30 cavers from 3 caving societies and the Karst Research Institute ZRC SAZU, supported by the company Postojnska jama d.d. Their work results in new discoveries of our famous system time and again. In 2015, the explorers extended the cave by as many as 3.5 kilometres and, earlier this year, they connected Pivka Cave and Magdalena Cave, thus discovering 180 new metres on the way to Planina Cave. They have also established that new measurements of Magdalena Cave were needed and discovered a promising connection with Lekinka Cave. Each Postojna Cave discovery is extremely important for understanding the incredible subterranean karst, which remains a mystery despite the many centuries of explorations and never fails to impress us with each new discovery.



Postojna Cave map with the recently discovered area clearly marked, source: Postojnska jama d.d.

Photos 1-7: Magdalena Cave, photo by Iztok Medja, source: Postojnska jama d.d.

Photos 8: Magdalena Cave, photo by Peter Gedei, source: Postojnska jama d.d.