Of the hundreds of caves in Bulgaria (mostly in the Stara Planina and western Rhodopes), several have been fitted with walkways and lighting and are open to the public. The most famous are the Magura Cave with its prehistoric paintings, the Yagodina Cave with its stalactites and cave pearls, and the spectacular Devil's Throat near Trigrad.  There are many other caves equally enticing known to the Bulgarian cavers but they welcome contact with their foreign counterparts.  Get in touch with the Bulgarian Federation of Speleologists and you can be sure to find someone who speaks English. 

At the time of writing no foreign operator offers package trips for rock climbing however you can hire equipment and a personal guide from Odysseia-In in Sofia at a cost of approx ₤12-15 per person per day.