Kızılelma - Cumayanı Cave System

which Kızılelma a cave of Turkey’s longest cave is situated in the district of Kızılelma Ayici village in Zonguldak province Gelik. Developed in the form of a sinkhole, the cave collects the waters of Ayiçi Dere and Aydın Dere. A 30 × 10 meter sized fossil is entered through the mouth and water is found 100 meters later. Underground system (Kızılelma- Cumayani) cavern with a total length of 10 kilometers, the second longest cave system in Turkey bears the title.