KőBánya

KőBánya is a flooded limestone mine under the Kőbánya district of Budapest, Hungary. The stone was cut to build the Parliament, the Castle and the Citadella. Winemakers later used the cellars, a brewery owned them from the 20th century, and during the Second World War a hidden aircraft engine factory worked here. Today the flooded rooms and cellars, with stairs instead of rails, are used for diving.

The main halls are open to the air, so they count as open water diving, and industrial objects left behind lie in the main hall. The smaller halls beyond are swum with torches under cave diving rules, and most of the underwater industrial remains can only be dived with a cave certification, though one spot is open to all divers. Deeper parts are for advanced divers only.

Divers drive into the mine and kit up near the water. The water is a constant 13 °C and clear, while the air is around 8 °C, so a thick wetsuit or drysuit with hood and gloves is needed, and at least two torches. A typical dive lasts about 40 minutes with a safety stop at 5 m.