Balaton Spa's
There are dozens of sulphur springs springing up around the lake, several of which have been well-known for centuries to people looking for cures. the most famous one is at hévíz, where the thermal water springs out at the foot of the mountain of keszthely. in reality, this is a geyser which pours its medicinal water at 38 degrees into a natural crater, forming a lake.
http://www.guideviaggi.net/english/bal_spas.htm