There is a cave visible on sat pictures: https://www.google.com/maps/place/40%C2%B009'53.3%22N+20%C2%B023'13.6%22E/@40.164793,20.3863688,335m/data=!3m2!1e3!4b1!4m40!1m35!4m34!1m21!1m2!1s0x40aa8682cb317bf5:0x400a01269bf5e60!2sSofia!2m2!1d23.3218675!2d42.6977082!3m4!1m2!1d21.6840789!2d40.2989227!3s0x1359cfe6019aa6b3:0x6fc2e489a4ba15b5!3m4!1m2!1d20.6220033!2d39.9153834!3s0x135bb733bba5698b:0xffed857d5be92a55!3m4!1m2!1d20.3580308!2d40.2344204!3s0x135a5796b50bc6e1:0xa6c4dcd3b4eb5d6a!1m6!1m2!1s0x135a57ec83674f23:0x338909e7d94bfae1!2sP%C3%ABrmet,+Albania!2m2!1d20.3517334!2d40.2361837!2m3!6e0!7e2!8j1754586000!3e0!3m3!8m2!3d40.164793!4d20.387116?entry=ttu&g_ep=EgoyMDI1MDgwNC4wIKXMDSoASAFQAw%3D%3D

A Bulgarian caving club is exploring it. There is an article about it (in Bulgarian): https://pod-rb.eu/blog/2023/10/17/%d0%b5%d0%ba%d1%81%d0%bf%d0%b5%d0%b4%d0%b8%d1%86%d0%b8%d1%8f-%d0%bf%d0%be%d0%b4-%d0%ba%d1%80%d0%b8%d0%b2%d0%b0%d1%82%d0%b0-%d0%ba%d1%80%d1%83%d1%88%d0%b0-2023/