Molnár János “MJ” Cave (Budapest)

Molnár János Cave, located in Budapest, is one of the largest active hydrothermal caves globally. Divers can explore about 6 km of its passages through a guided dive operation. The cave was discovered in 1854, and diving began in the 1950s, but it is now strictly regulated for safety. Unique features include warm thermal waters and an interesting dive history, where divers often swim beneath buildings and streets. Recent dives have revealed complex underwater formations, requiring careful planning due to temperature changes experienced at different depths.