Most of Hungary are plains, which are not very interesting to the geologist or the speleologist. Young clastic sediments, deposited by lakes and rivers, are not karstified at all. Only 1.5% of the surface is covered by carbonatic rocks with caves.
The northern part, along the border to Slovakia, belongs to the Carpathian Mountains. However, it is not a mountain ridge, it's a low hill country. Here are the famous cave regions of Aggtelek and Lillafüred. Other karst areas are at the Balaton, in the south and along the western border to Austria. These areas are also hill country.