Location: Kirklareli, Demirkoy District
The cave is located inside the border of Sarpdere village of Demirkoy district, in Kirklareli. It is at 5-6 km. southwest of the village. The cave could be reached via vehicles like jeep or tractor.

Properties: The cave has three entrances. The cave is an underground system with the total length of 3200 meters. The first 1000 meters after the entrance is water. The spring born from the cave forms the Rezve Creek, which forms the Turkish – Bulgarian border. The first of the entrances is Dupnisa Dolin entrance. The second entrance is a dry cave and starts with two separate entrances. One of the branches is 456 meters long and the other branch is 363 meters long. The third entrance is the Kiz Cave and starts with a slope of 60 degrees. The sub branches of the cave is fossil and the main system is active. There is a saloon with dimensions 150x 60 meters.