entrance of bolii cave ( pestera bolii ), near petrosani city, hunedoara county, romania.

cave bolii cavern speleology petrosani amazing bat beautiful bridge chalk ceiling column dark disease entrance environment formation geology gray green hunedoara impressive illuminated karst landmark landscape limestone nature natural old outdoors river rock romania scenic stalactite stalagmite steam stone subterranean travel tour tourism tunnel underground underworld water wild pestera city county artificially open visitors