
János Molnár is a vast underground cave, located right under Budapest. The depth of the cave is approximately 100m and the width is 3km. The cave is made out of thermal karst springs, spewing from the depths and it is one of tje biggest thermal caves in the world. The tepmerature of water fluctuates between 25-27°C.
After the beer factory stopped pumping, groundwater levels raised and partly flooded the underground mine system where you can now dive. The water is crystal clear and visibility is awesome.