Rajko’s Cave has the Rajko river flowing through it. It consists of a sinkhole and a spring, and both have a lower – hydrologically active, and a higher – dry horizon. Based on the length of the explored channels of 2,304 m, it is considered the longest cave system in Serbia. Visitors can currently access around 850 m of the 1,410 m long circular path, created by joining the river and dry canal. Rajko’s Cave is rich in various cave jewellery made of snow-white crystalline calcite, which is considered the best quality in Serbia. The gurgling of the Rajko river that echoes in the cave spaces, especially in “Hedgehog’s Hall”, with thousands of calcite tubes on the ceiling, leaves a very special impression.