Molnár János-barlang

Useful Information

Location:	Frankel Leó út 48, 1023 Budapest. (47.5181319, 19.0359332)
Open:	No restrictions. [2022]
Fee:	free. [2022]
Classification:	Karst Cave Hypogene Caves
Light:	diving equipment provided
Dimension:	L=6,000 m, VR=130 m, Twater=25 °C. Cadaster 4762-5.
Guided tours:
Photography:	allowed
Accessibility:	no
Bibliography:	Gergely Surányi, Endre Dombrádi, Szabolcs Leél-Össy (2010): Contributions of geophysical techniques to the exploration of the Molnár János Cave (Budapest, Hungary) Acta Carsologica. 39 (3). Slovenian Academy Of Sciences and Arts: 565–576. ISSN 0583-6050. online DOI
Address:	Molnár János-barlan, Frankel Leó út 48, 1023 Budapest, Tel: +36-70-389-8939. E-mail:
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then. Please check rates and details directly with the companies in question if you need more recent info.

History

1856	dry passages of the cave first explored by János Molnár.
1937	surveyed by Ferenc Papp and Sándor Tarics.
1950s	first diving explorations.
1970s-1980s	divers of the FTSK Delfin dive club successfully explored and charted more than 400 m.
1977	cave named after János Molnár.
1982	cave becomes a highly protected cave.
2002	new passage discovered, and cave extended to 6 km.

Description

Molnár János-barlang (János Molnár Cave) is a water-filled cave in Budapest which is used for diving tours. In a way it is a tourist cave, although the minimal requirements for a visit are a valid diving licence. There is a dive center at the cave which offers cave diving as well as diving in the Kőbánya Mine.

The cave is water-filled, there are only very few air-filled sections. The main entrance is a spring with an artificial pond in Frankel Leó út named Malom-tó (Malom Lake), the entrance is in the middle of the pond. With a length of 6,000 m it is the longest active thermal cave in Hungary. Malom translates "mill", the lake was the reservoir of several mills on the small ledge between the hill and the Danube. Today the lake is drained through a sluice and canal under the Lukács Bath into the Danube. Right above the lake on the hillside is the other entrance, which leads down and soon ends at the water table. The octagonal building on the left side is the . The terace on the right side was a popular cafe only a few years ago, but is abandoned.

The cave was named after János Molnár (*1814-✝1885). He was a forensic chemist and caretaker of the pharmacy at the Rókus Hospital in Pest. His connection to the cave is that he was the first who explored the dry passages in 1856, when the cave was still named Langyos-forrásbarlang. He analyzed the chemical composition of the thermal water. He published his results in 1858 in the 33rd issue of Orvosi Hetilap (Medical Weekly). Ferenc Papp published in 1942 the book Budapest meleg gyógyforrásai (The Warm Springs of Budapest) where he proposes to rename the cave. This actually happened in 1977, when the first articles were published which used that name, although some still used the old name. There were other names too, like Malomtó-forrásbarlang after the lake, Szent Lukács barlang, and even Szt. János-barlang. In Hungarian, it is normal to write names with the surname first, that’s why the cave is named Molnár János-barlang. Obviously, the translation is thus János Molnár Cave, but it seems the Molnár János Cave and MJ Cave is propagated by the dive school and even made it in the Wikipedia page.

The exploration of the underwater part started in the 1950s with first dives, but the technology was not suffucient. This changed in the 1970s, and over several years the divers of the FTSK Delfin dive club explored and surveyed more than 400 m. Then exploration stalled. This is part of the cave is today called the "old part". The new part was discovered in 2002 and soon enormous passages were found. A waterfilled chamber, 86 m long, 27 m wide and 15 m high is quite impressive. And at the moment [2025] the cave has been explored for a total length of 6 km, and there is still potential for more.

Soon after the cave divers got the permission to offer cave diving courses in the cave, although with restrictions. The cave is a "highly protected cave", which seems to be the Hungarian version of a Natural Monument. At the same time 10 divers are allowed daily.