 Jomblang cave ("Luweng Jomblang") and Grubug Cave ("Luwung Grubug") located in the Semanu subdistrict in Gunungkidul, as well as other caves in the area, are well-known to local caving (speleological) groups.Some of the caves are quite long; Cerme cave, for example, has an entrance in Bantul Regency and stretches for quite a distance eastward into Panggang subdistrict in Gunung Kidul Regency.The Geopark has many caves, some of which have underground rivers.