Hranická propast (CSAK KUTATÁS / research only)
Diving is prohibited for the public: only authorised research teams dive here. The Hranice Abyss on the right bank of the Bečva river is the deepest known flooded freshwater cave in the world. The dry part is 69.5 m deep and the flooded part has been measured to 450 m by ROV in 2022 without reaching the bottom, a total of more than 519.5 m. A 2020 study suggests the flooded shaft could reach about 1 km. The site lies in the Hůrka u Hranic national nature reserve; the dry abyss can be viewed from a fenced platform.
Facts
- Region: Czechia – Caves, Abyss & Mines
- Area: Hranice Karst
- Depth: 0–450 m
- Level: advanced
- Current: low
- Type: cave
- Coordinates: 49.532, 17.75078
- Highlights: deepest known flooded freshwater cave in the world, dry part 69.5 m, flooded part measured to 450 m by ROV (2022), bottom not reached, CO2-rich mineral water, rebreather-only expedition diving, national nature reserve Hůrka u Hranic, fenced viewpoint over the dry abyss
- Permit: Only authorised research teams may dive. Cave exploration or research needs permission from the nature-protection authority (Act 114/1992 Sb. §10(3)); for a national nature reserve this is the regional AOPK ČR office (here Olomoucko), per portal.gov.cz. One secondary source says permission is also issued by the Czech Diving Association to speleodivers for research only (not verified at the primary source). The research group's page says its work runs under an exemption from the Act.
- Issuer / contact: AOPK ČR – Regional office Olomoucko
- Phone: +420 951 425 136
- Email: olomoucko@aopk.gov.cz
- Address: Lafayettova 13, 779 00 Olomouc
- Website: https://aopk.gov.cz/web/cz/rp-olomoucko
- Closed / banned site: True
- Unverified: Depth figures conflict: project page shows 519.5 m total/450 m water in text but 473.5 m/404 m in its footer; the ~1 km figure is a 2020 study estimate. The exact permitting body (AOPK regional office vs. Czech Diving Association) is not confirmed by a primary source.
- Tips: Not open to recreational or technical divers. Research dives are run by the local Czech Speleological Society group ZO ČSS 7-02 Hranický kras (with Czech/Polish teams) under an exemption from Act No. 114/1992 Sb. Expedition dives use rebreathers (one source: open-circuit is not used). A diver died here in August 2026 at about 186 m, so treat it as an extreme-risk site. Visitors can walk from Teplice nad Bečvou station along the nature trail (about 500 m) and look into the fenced dry part.