Cueva Molnár János

Underwater thermal cave

Hungary · Rózsadomb, Budapest; 200 m from the Danube

Profundidad: 5–40 mNivel: Technical (Cave Diver); only with a guide from the local operatorAll year round

A flooded thermokarst system beneath a residential district of Budapest, with more than 5.5 km of surveyed passage and sections reaching 100 m deep. It is one of the largest active thermal water caves in the world and one of the very few open to certified cave divers. In 2008 a lake was located inside it with a main chamber some 86 m long, 27 wide and 15 high.

Depth

5–40 m

Recommended level

Technical (Cave Diver); only with a guide from the local operator

Current

Gentle, rising because of the thermal inflow

Access

From the street, through an unmarked door next to some old 19th-century baths

Best time

All year round

Plan your dive

Best time: All year round

Did you know

Es un caso muy raro de cueva cálida: el buceo en cueva suele hacerse entre 4 y 15 °C, y aquí las capas superiores están a unos 27 °C, bajando a 20 y luego a 17-18 °C conforme se mezcla el agua fría de las colinas de Buda. La cueva sigue creciendo: el agua cargada de sulfhídrico y CO₂ va disolviendo la roca. Parte de ese agua alimenta todavía los baños Lukács por una conducción subterránea. Buceo en cueva en pleno centro de una capital europea, a 200 m del Danubio.

Sources consulted: Wikipedia (Molnár János Cave); CNN Travel (2025); SSI MyDiveGuide