4250 caves are known in Bulgaria until now. A great part of the territory of the country is covered by carbonate rocks. Among them are 3 sandstone caves and 60 caves in volcanic rocks. Bulgaria has 6 show caves.
The longest caves are Duhlata (L=17,500m),
Orlova Čuka
(L=13,437m), and
Iagodinska Peštera
(L=8,250m).
The deepest caves are Raychovata Dupka Cave (-372m), Barki N14 (-350m), and
Kipilovo (-350m).
The deepest shaft is found at Druzhba (-130m).
However, the Bulgarian cavers were very successful during the last years in
discovering and exploring new caves, so this may change.