Divje jezero (Wild Lake)

A small emerald lake below a cliff near Idrija that is really the mouth of a steep, water-filled karst shaft. Cave divers have explored the siphon since 1957; in 1995 they reached 124 m, and it has now been explored to about 160 m. The water stays at 7–10 °C, olms live in the cave, and after heavy rain the spring can surge to around 60 m³/s. Several divers have died exploring its depths, so this is purely an extreme exploration site.

Facts

Region: Slovenia – Lakes, Rivers & Caves
Area: Idrijca valley & Idrija
Depth: 0–160 m
Level: advanced
Current: moderate
Type: cave
Coordinates: 45.982, 14.0283
Highlights: deep karst spring shaft – a vertical siphon/sump below a small lake, explored by divers to about 160 m, divers reached 124 m in 1995, water 7–10 °C all year, olm (Proteus anguinus) in the cave, floods up to 60 m³/s after heavy rain, several divers have died here, natural monument since 1967
Permit: Double protection: (1) natural monument since 1967 and part of the Zgornja Idrijca landscape park (Idrija municipal decree, 1993): visiting the cave is prohibited except for research; minor deviations need the prior consent of the competent nature-conservation service, and the inter-municipal inspectorate (Idrija, Logatec, Vrhnika) supervises. (2) As a cave it falls under ZVPJ: 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: the 1993 Zgornja Idrijca landscape-park decree bans visiting the cave except for research, and sport activities harmful to the natural monument are prohibited. Not available to visiting divers – no recreational or guided diving exists. Deep trimix exploration with cold water, flood risk and a long fatal-accident record. The state technical-diving unit has also trained here.

Divje jezero (Wild Lake)

Facts

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