The origins of Lake Hévíz go back to the ancient times when Lake Balaton and the basalt mountains around the lake were formulated. At the end of the Pannon-era volcanoes disrupted the layout of the Trans-Danube region. The healing power of the water was already known to our ancestors. The first signs of post-volcanic activity were the spring of heat sources, as was the eruption of “Ancient Hévíz”.
Archaeological excavations prove that this area was inhabited even at the end of the Stone Age. The art relic church on Egregy hill was built during the reign of the Árpád-dynasty, which uniquely preserved the reminiscence of the era.
Lake Hévíz is the world’s largest biologically-active natural thermal lake, which is able to refresh body and soul alike. Lake Echo of New Zealand is larger and its water is warmer, but it cannot be compared to the particularities of the Hungarian lake as it is not suitable for bathing and cannot be used for medical purposes.
The source of the 4.4 ha water surface lake, rich in sulphur, radium and minerals, can be found 38 metres deep in the cave, which due to its high well capacity completely changes in every 48 hours. The water of Lake Hévíz contains an equal proportion of dissolved and gaseous substances, thus unifying the favourable characteristics of thermal waters rich in carbonic acid, sulphur, calcium, magnesium, hydrogen carbonate and slightly radioactive substances.
Water temperature may reach 23-25 °C in winter and 33-36 °C in summer. The water of the lake is in a constant move. On the one hand, it is moving from left to the right, and on the other hand, warm water moves upwards while cold water goes downwards. This two-way flow keeps the water of the lake in a constant move, thus leaving a special massaging effect on the human skin.
In winter it provides a spectacular and unique experience when the condensed steam forms a steam cap on the top of the lake surface. This “cap” prevents water from cooling down, and at the same time a natural inhalatorium is formed. Hydrogen sulphide and radium emanation are released into the air, which have medical effects on the exhausted vocal cords when inhaled.
According to the memoires from the Roman era, the oldest and most famous thermal bath in Hungary can take pride in a history of over 2,000 years.
Lake Hévíz, together with the volcanic hills of the Tapolca basin and those of the Tihany peninsula were included in the recommendation list of the World Heritage National Hungarian Committee in January 2003.