The Thermal Lake of Hévíz is the world’s largest biologically active natural thermal lake. It is located in a unique setting, a mere 6 km from the Lake Balaton, 198 km from Vienna and 193 km from Budapest. The lake’s formation goes back to ancient times. At the end of the Pannon-era (named after its sea), volcanoes broke up the layout of the Trans-Danube region. The 4,4 ha water surface lake's source rich in minerals can be found 38 m deep in the cave, where tens of thousands of years old warm and cool karst waters are mixed. Hévíz bathers have experienced that the water’s depth varies between 150 and 200 cm. You can stand up around the edges and sink thigh-deep into the softened and healing turf mud.