You can descend to the valley, where the Harmankaya Waterfalls (Harmankaya Şelaleleri) in the city centre of Zonguldak are located, through a narrow path in the forest. In most parts of the valley, there are paths that are 10 meters wide. After an average of 1,100 meters of hiking in the valley, you can see the first waterfall. After an uphill climb just past the first waterfall, proceed 20 meters on the path between the bushes and descend to the valley, at the top of the first waterfall flow. Another 250 meters from this spot is the second waterfall. Here, after a 30-meter climb in the forest next to the waterfall, you will walk down a 20-meter path and see the second waterfall. After walking a little further in the valley, you will come to the third waterfall. Lush green flora surrounds visitors along this trail. In the forest area within the valley, you may come across plants and trees such as chestnut, oak, hornbeam, linden, buxus, cranberry, alder, poplar, plane, blackberry, arbutus, wild apple, wild cherry, wild hazelnuts, bay, medlar, wild grapes, rowanberry, wild pear, rhododendron, blackberry, and rosehip.
The first speleology studies in Zonguldak, one of the richest regions of our country in terms of cave formation, began in the early 1970s. Numerous local and foreign scientists have conducted research in the caves of Zonguldak, which have also been used for sporting trips. Almost all the caves in Zonguldak are active and feature unique beautiful geological formations like stalagmites, stalactites, and travertines, as well as streams or lakes.
Gökgöl Cave (Gökgöl Mağarası) is located at the Zonguldak entrance of the Zonguldak-Ankara highway, on the right side of the road. The cave features travertines, stalactites, and stalagmites. The first 875 meters of Gökgöl Cave can be visited. This illuminated has a walking path, bridges and viewing terraces.
The Cehennemağzı Caves (Cehennemağzı Mağaraları) are in the city centre of the Ereğli district. There are three caves used in the Roman and Byzantine periods.
Kilise Cave (Kilise Mağarası) is a natural cave which is also a rock-cut structure. It was used as a Christian shrine during the Roman and Byzantine periods; in the early days of Christianity, the religion was not officially accepted by the Roman Empire, thus the early Christians used to worship in this cave secretly.
According to the legends, Hercules (Herkül), who came here during the legendary Argonaut Campaign in BCE 1200, completed in this cave the most difficult of the 12 tasks ordered by King Eurystheus. Hercules entered the cave and went to the underground realm of the god Hades (the god of hell). From there, Hercules brought Cerberus, the three-headed dog guarding the entrance of hell, back to the world. The city was named Heracleia Pontica (Black Sea Ereğli) after Hercules, since his twelfth mission was achieved in the cave, thus saving the Mariandiyns, the inhabitants of Ereğli at that time, from the tyrant rulers.
Ayazma Cave (Ayazma Mağarası) has a wide entrance and two halls. In one of the halls is a lake, once considered sacred. The lake was also used as a cistern, providing the region’s water requirements. In the area on the left side of the entrance, classical music performances are organized.