Hévízi-forrásbarlang

The spring cave that feeds Lake Hévíz, Europe's large peat-bottomed thermal lake, opens at about 38 m depth at the bottom of the lake's spring crater. Several springs discharge water of roughly 35–40 °C, alongside a cooler spring of about 21–24 °C, and the mixed water in the cave stays around 38 °C. Divers have entered the crater since 1908, and modern dives are research dives measuring temperatures and sampling water. It is a strictly protected cave inside a working medicinal spa lake.

Facts

• Region: Hungary – Caves & Mines
• Area: Balaton Uplands & Bakony
• Depth: 38–40 m
• Level: advanced
• Current: moderate
• Type: cave
• Coordinates: 46.786822, 17.192817 (approximate)
• Highlights: thermal water ~38 °C, springs of 35–40 °C plus a cold spring ~21–24 °C, spring cave at ~38 m below a medicinal lake, peat-bottomed spring lake
• Permit: Custodian consent from the Balaton-felvidéki National Park Directorate (Nature Conservation Act §51(4); Decree 17/2021 (IV.9.) AM Annex 4: Hévízi-forrásbarlang max 20 persons/day), with a qualified dive leader (MBSZ cave dive leader + 'cave diver III' or equivalent), for a specific date. Research dives need a separate research permit from the Zala County Government Office (2026 procedure on application of the Hévíz Szent András rheumatology hospital, ZA/KTO/00698-2/2026). Coordination with the spa lake operator is required; realistically only organised via the operator or a research team.
• Issuer / contact: Balaton-felvidéki National Park Directorate
  • Phone: +3687555260
  • Email: bfnp@bfnp.hu
  • Website: https://www.bfnp.hu/
  • official contact page not machine-readable; phone/e-mail from public directory listings (8229 Csopak, Kossuth u. 16.) - verify
• Tips: Legally listed for non-research cave diving (max 20 persons/day), but no organiser offers dives and the lake is a medicinal spa operated by the Hévíz spa/hospital: in addition to the national park consent you would need the lake operator's agreement. Deep, hot-water technical cave diving (overheating risk in a wet/dry suit, thermometers hard to read). Full cave + technical qualification only.

Sources

• https://njt.jog.gov.hu/jogszabaly/2021-17-20-7R
• https://termeszetvedelem.hu/_user/browser/File/barlangkutat%C3%A1si%20jelent%C3%A9sek/2008/hevizgyogyfurdo_2008.pdf
• https://termeszetvedelem.hu/_user/browser/File/barlangkutat%C3%A1si%20jelent%C3%A9sek/2016/hevizgyogyfurdo_2016.pdf
• https://kormanyhivatalok.hu/system/files/dokumentum/zala/2026-02/za_kto_00698-2_2026.pdf