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.
Tiefe: 38–40 m