Wall/Cave
Lastovo Island
Croatia
CroatiaUp to 35 m · Open Water
Spiny lobsters · European lobsters
See dive siteA 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
It is a very rare example of a warm cave: cave diving is usually done at between 4 and 15 °C, and here the upper layers are at about 27 °C, falling to 20 and then to 17-18 °C as the cold water from the Buda hills mixes in. The cave is still growing: water laden with hydrogen sulphide and CO₂ is gradually dissolving the rock. Some of that water still feeds the Lukács baths through an underground conduit. Cave diving right in the centre of a European capital, 200 m from the Danube.
Sources consulted: Wikipedia (Molnár János Cave) · CNN Travel (2025) · SSI MyDiveGuide
Which other dive sites are like this one?
Same type of dive: Cave / cenote
Same type of dive: Cave / cenote
Same type of dive: Cave / cenote
Based on what we already know about this dive site.
Access
From the street, through an unmarked door next to some old 19th-century baths
Best season
All year round
Same type of dive: Cave / cenote
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