Cave Diving beneath Budapest.
Budapest is divided by the river Danube. Buda is situated on the west bank while Pest is on the east. The hills of Buda are inhabitated since the Roman times, and it was famous about its thermal water springs. Only meters from the Danube river one finds the submerged Molnár János cave, an active thermal water cave.
The cave is a good example of modern phreatic hypogenic caves, since it has been formed by mixing corrosion below the water table. Mixing corrosion occurs where flow systems of different orders (with different chemistry and temperature) meet via tectonic lines or through diffusion. Besides the tectonic control, the network maze of cave passages follows the south-southwestward dip of the Upper Eocene limestone and marl.