Križna jama / Nova Križna jama – deep sump
Križna jama is famous for its chain of underground lakes behind fragile calcite dams; downstream, the water continues through a siphon over 124 m deep towards Nova Križna jama (Dihalnik in Grdi dol). Divers reached 70 m there in 1994 and 124 m in 2009, and in July 2026 nine Slovenian, Belgian, French and German divers reached 153 m and found new passages, described as the most demanding Slovenian expedition in 17 years. The water is about 8 °C and very clean; the 2026 team found no olms. The cave is among the world's richest cave-fauna sites.
Facts
- Region: Slovenia – Lakes, Rivers & Caves
- Area: Notranjska & Brkini (Cerknica, Postojna, Pivka)
- Depth: 0–153 m
- Level: advanced
- Current: low
- Type: cave
- Coordinates: 45.74416667, 14.46444444
- Highlights: chain of 22+ underground lakes behind calcite dams, downstream siphon over 124 m deep towards Nova Križna jama, July 2026 expedition reached 153 m, water about 8 °C, no olm found in 2026, one of the world's richest cave-fauna sites, cave-bear bone site
- Permit: Since the 1990s the cave has been cared for by Društvo ljubiteljev Križne jame (Križna jama society); under ZVPJ they must be notified in advance. Under the Cave Protection Act (ZVPJ) every cave, including water-filled ones, is state-owned and protected. Only persons certified for independent caving (certificate checked by the Speleological Association of Slovenia, JZS) may explore caves, and they must notify the cave's custodian, concessionaire or protected-area manager in advance (Art. 14); closed caves can be entered only for scientific/archaeological work with a permit from the ministry responsible for nature conservation (Art. 17). There is no visitor dive permit: in practice diving here happens only as a member of the caving/cave-diving team that runs the exploration.
- Issuer / contact: Ministry of Environment and Spatial Planning – Nature Conservation Sector
- Phone: +38614787335
- Email: gp.mop@gov.si
- Website: https://www.gov.si/teme/podzemne-jame/
- Tips: Research-only, not available to visiting divers: such expeditions happen roughly once a decade, with rescue institutions informed in advance. Tourists can visit the lakes only on guided boat tours (water section limited to 4 visitors a day). Calcite dams are extremely fragile; sudden floods trapped a tour group for almost three days in January 2024.