The Kungur ice cave

A gypsum cave on the right bank of the Sylva in Perm Krai with ice in it all year. Peter the Great’s decree sent the geographer Semyon Remezov to document it in 1703, it has been taking visitors since 1914, and over five million people have now been through, about 100,000 a year. The grottoes are named and the names tell you what is in them: the Giant, the Long Grotto with an underground lake, the Ethereal, the Tower, Dante, and the Diamond Grotto, which keeps its frost and icicles through the summer because cold winter air sinks into the entrance passages and has no way to drain out again. Three routes, 1.5 km in about 80 minutes, 1.8 km in 100, or 2 km with a laser show in 90. Near the town of Kungur.