- Luweng Jaran cave is known as the longest cave in Indonesia and even the latest data showed that this cavern is the longest in the world. This cave is an expedition attraction that is now only open for experienced and pro visitors, not for public as the locations is not easily accessible, dangerous, and need special skill to enter the hole of this cave.
In 2002, this cavern is registered as the longest cavern with the total length is 24 km. Located in Punung Dustrict, Pacitan Regency of East Java, just 30 km from the city center. First found by local people and then explored by Anglo-Australian Expedition Team and Indonesian Cavers in 1984. The first mapping reached to 11 km and in 1992 the expedition find the Luweng Jaran connected to Luweng Punung Plente, and the length became 19 KM. On rainy season this cave is dangerous as here located swallow hole where river disappears from the ground surface. In 1986, the Asian Caving Expidition explored the cavern and they stated that the beauty of this cavern can only be compared to that they had explored in Mexico.
- Luweng Jaran has some stalactites that pints upward not downward as common stalactites. Also there are crystal color stalactites. There is other statement from the cavers explorers that Luweng Jaran was a significant archaeological study source that are pointing prehistoric past of Sewu.