Molnár János Cave
The Molnár János Cave is a thermokarstic water-filled cave system. It is located in the Rózsadomb district of Budapest in Hungary.

The deepest sections reach , while the total length of explored sections is currently . The cave mouth is just  from the Danube.

In 2008, a cave lake was found there, with largest chamber roughly  long,  wide and  high.

References 

Caves of Hungary
Geography of Budapest
Underwater diving sites in Hungary