grotta di frasassi, genga, italy. inside one of the most extensive caves in italy. lake in the cave,

cave formation quail caving stalagmite geology wadi stalactite tunnel painting canyon rock arch temple terrain person carving infrastructure grotta frasassi genga italy europe lake nature stone cavern stalagmites vertical closeup white landmark famous park excursion guide indoors spooky background natural dark darkness lights travel underground landscape mountain wall light tourism limestone rocks grotto ancient tree water petra inside one most extensive caves stalactites italy