Lake Cerknica – Rešeto sinkholes
Lake Cerknica is Slovenia's largest intermittent lake; part of its water drains through the Rešeto sinkholes in the middle of the lake towards springs at the edge of the Ljubljana Marsh. In spring at high water you can visit all three large sinkholes in under an hour, following the deepened channels that lead into them down to about 10 m, where the bottom is rocky and cracked. Because Rešeto dries out completely every summer there are no fish, only small invertebrates – and human footprints preserved in the mud at 8–9 m. The local club DPD Rak holds an Easter dive with a blessing of diving equipment here every March or April.
Facts
- Region: Slovenia – Lakes, Rivers & Caves
- Area: Notranjska & Brkini (Cerknica, Postojna, Pivka)
- Depth: 0–10 m
- Level: beginner
- Current: low
- Type: bay
- Coordinates: 45.77194, 14.3576
- Highlights: three large sinkholes (ponors) with rocky, fissured bottoms, human footprints in the mud at 8–9 m from the dry season, submerged embankment, marsh plants, water beetles, snails, caddis larvae, water fleas, annual Easter dive with blessing of equipment
- Tips: Legal status: the site lies in Notranjska Regional Park (Odlok o Notranjskem regijskem parku, Uradni list RS 75/2002) and in the Cerknica Lake wetland zone. Neither that decree nor the 2015 navigation decree for Lake Cerknica mentions diving or swimming (they ban motor craft, motor/electric model boats and changes to the sinkholes; boating is only allowed above set water levels). Whether the park manager (Javni zavod Notranjski regijski park) expects divers to notify it or get consent could not be confirmed; ask the park before diving. From Cerknica drive through Dolenje Jezero to the large paved visitor car park before the Stržen bridge; kit up there and walk along the road to Rešeto. The shore is gentle everywhere – stick to the cart tracks where the ground is firmer, especially for the exit. Study a map or aerial photo first and navigate by compass. Only diveable at high water, typically March–April; water 3–15 °C. The site dries out completely in summer. The SPZ sheet dates from 2012; river gravel, banks and access roads may have changed since.