The Smelly Cave of Turia can be found on the Balvanyos pass, in the side of the Smelly Mountain, at a 1052 m altitude above sea level. The 14 m long cave is Europe’s largest hydrogen sulfide mofetta, from where approximately 3000‒6000 m3 gas evaporates daily. According to the Hungarian chemist Lajos Ilosvai’s analysis (1884), the composition of the emanating gas is as follows: 95.82% carbon dioxide (CO2), 2.66% nitrogen (N2), 0.38% hydrogen sulfide (H2S), 0.14% oxigen (O2). The cave received its name from the characteristic smell of the emanating hydrogen sulfide.

The hollow is not a natural formation, it was the abandoned adit of a sulphur mine. According to the testimony of princely patents, Turia used to possess the privilege of sulphur production. Later the smelly cave entered the possession of the Apor family; in 1892 Gábor Apor had the hollow walled with carved stones. At present the cave can be visited freely; for safety reasons its lower back part has been closed with iron bars. Its therapeutic use is recommended for people suffering from rheumatism and vascular diseases.