Macocha Abyss, Blansko, Czech Republic

It is a popular tourist attraction for casual visitors to the region, in addition to cavers and advanced technical divers.
Description
At the beginning of the Pustý Žleb (Desolate Canyon), below the town of Sloup, the waters of the Sloupský Brook, one of the tributaries of the subterranean river Punkva, helped to form an extensive system of underground passages, domes and abysses, measuring approximately 6.500 meters, known as the Sloupsko-šošůvské jeskyně (Sloup-Šošůvka Caves). At 3.000 meters long the viewing circuit is the longest underground trail open to the public in the Czech Republic. While the Sloupsko part features large domes and deep abysses, the Šošůvka caves section, on a somewhat smaller scale, is remarkable for its amazing fragile and colorful dripstone formations. One of the stalagmites, called "Svícen" (Candle), has a lace-like collar an effect created by sinters. Part of the circuit includes the tunnel-like cave known as "Kůlna" (Shed), which has been the subject of much archeological work.