The underground river
Running through the system, making lakes and falls.
Vassia Atanassova - Spiritia — Public domain · Hubertgui — Public domain · Hubertgui — Public domain
Duhlata is **the longest cave in Bulgaria**: a network of passages totalling more than eighteen kilometres across six stacked levels inside the marble of Mount Vitosha, with an underground river running through it. The system is unusually complex — chambers, tight passages, lakes, internal waterfalls and calcite formations — and parts of it are still being explored. It was found in the 1950s and mapped over decades. **Read this carefully: Duhlata is not a show cave.** There is no lighting, no made path, no railing and no ticket office. Going in is genuine caving and requires a **qualified guide, equipment, a helmet and lighting**, arranged through the Bulgarian caving clubs. Entering without them is a real danger rather than an adventure. Anyone wanting a cave equipped for an ordinary visit should choose **Saeva Dupka** or **Ledenika** instead — both lit and run with guided tours.
Running through the system, making lakes and falls.
A stacked system still being explored in parts.
Near Bosnek village, southern slope of Vitosha
Bulgaria has more than five thousand caves, six of them equipped for ordinary visits with lighting, paths and guided tours. Closest to Sofia is **Saeva Dupka**, about 100 km north, with five chambers and acoustics good enough that concerts are sometimes held in it, and **Ledenika** near Vratsa, which has ice formations in winter. The most famous of all is **Devetashka Cave** — an enormous chamber with seven openings in its roof letting down columns of light, internationally known from photographs, but **partly closed during the bat breeding season**, so check before going.