Jomblang Cave, Cave system in Yogyakarta, Indonesia

Jomblang Cave is a cave system in Yogyakarta featuring a steep vertical entrance shaft that descends roughly 80 meters down into the ground. Beyond this dramatic opening lies a network of limestone passages that wind through the underground for about 300 meters.

The cave formed thousands of years ago when water dissolving limestone created a massive sinkhole in the karst terrain of Central Java. This gradual geological process shaped the dramatic entrance and passages visible today.

Local people call the cave Luweng Jomblang, from the Javanese word luweng for a sinkhole or well. A folk story passed down in the villages holds that during the colonial era the government used the cave to dispose of the bodies of people suspected of being members of the PKI.

Visitors descend using ropes and harnesses as part of a guided group tour that requires basic fitness and comfort with heights. The passage can be slippery and physically demanding, so proper footwear and preparation help make the experience safer.

The light shaft comes through Luweng Grubug, a second opening 90 metres above the floor, reached by a sloping tunnel about 270 metres long from the base of the 50-metre entrance shaft. The beam appears only around 11:00 to 12:00, and only when the sky outside is bright.