Dryanovo cave is a complicated, four storey labyrinth of galleries and branches. In the course of time the rivers formed the cave galleries and halls, this happened within the Early Tertiary and Quaternary. This was the initial period of the cave formation. The effect of water on the limestone rocks has, over hundreds of thousands of years, gradually sculpted the beautiful cave forms; stalagmites and stalactites giving them various bizarre shapes. The impressive lights offer to visitors the chance to see these strange forms of nature with names given by human imagination: The Rain Hall with the Stone flower, the Willows, the Lake of Happiness and the Concert Hall which is situated 18m above the entrance and has excellent acoustics for any singers who visit.