The Hévíz thermal lake is a natural geothermal lake located in the town of Hévíz, Hungary, approximately 8 kilometers from the southwestern shore of Lake Balaton. It is the largest thermal lake in Europe and the second-largest in the world, with an area of about 47,500 square meters.

The lake is fed by a hot spring, which emerges from a depth of 38 meters at a temperature of 38°Celsius (100°Fahrenheit), making it a year-round destination for visitors seeking a warm and relaxing soak. The water in the lake is known for its healing properties, as it contains a variety of minerals such as calcium, magnesium, sulfur, and hydrogen carbonate, which are believed to aid in the treatment of various ailments, including rheumatoid arthritis, joint and muscle pain, and skin conditions.