Heviz Thermal Lake is the world's largest natural thermal lake suitable for bathing, spanning approximately 4.4 hectares. Water temperatures range from 24C in winter to 36C in summer, fed by artesian thermal springs pumping 410 liters per second that completely replace the lake's water every 72 hours. The waters have been renowned for their healing properties since Roman times, rich in minerals beneficial for joints and the musculoskeletal system. Unique tropical water lilies cover the surface creating an enchanting landscape. A major renovation project is underway through 2027 with temporary access via the Festetics Day Spa entrance