Rötelseehöhle, Natural cave monument in Gmunden, Austria.

The Rötelseehöhle is a natural cave near Gmunden that extends about 391 meters through limestone layers with multiple underground passages. The cave displays typical geological features of the Upper Austria region and offers views into the natural karst landscape.

The cave lies in the western flank of the Rötelstein at 600 m above sea level on the east shore of the Traunsee. Its passages have been surveyed to 391 m in length with a height difference of 53 m. The cave is a protected natural monument. Access for exploration starts from Karbach.

The cave is a designated natural monument (Naturdenkmal) of Upper Austria, listed under cadastre number 1618/1. Its lakes are linked by sumps, and the submerged continuation can only be entered by cave divers. An old walkway once crossed part of the northeastern passage; its iron supports are still anchored in the rock.

Access to the cave requires contacting local authorities and is not always freely available. Visitors should bring sturdy shoes and a light source to navigate safely through the underground passages.

From the lake's shore, a former wooden walkway once led halfway along a narrow 20-metre continuation on the north-east side. Its old iron supports are still anchored in the rock, while the passage beyond lies underwater and is reserved for cave divers.