Today, the Irkut­sk cave is con­sid­ered the longest in Rus­sia. The under­ground labyrinths in the Angara region have been explored for almost 100 years, and spele­ol­o­gists have already explored more than 70 km of branch­ing pas­sages. Under­ground cav­i­ties in lime­stone and sand­stone were formed about 1.5 mil­lion years ago. In 2019, a spele­o­log­i­cal expe­di­tion dis­cov­ered skele­tons of pre­his­toric bears in a remote part of the cave, the age of which exceeds 700 thou­sand years. Researchers divide the unique dun­geon in the depths of the moun­tain range in two: the “Old World” with a sys­tem of nar­row tun­nels in which it is easy to get lost, and the “New World”, where you can walk at full height. Botovskaya Cave is open to tourists, but the road to it takes a lot of time and effort. There are six entrances to the cave sys­tem, all of them are locat­ed in a dense for­est, so it is bet­ter to go with a guide.