After a series of large eruptions that ended forty thousand years ago, the volcano Uzon collapsed, the earth sank below it — a caldera formed. The diameter of the caldera is about 10 kilometers, and in it, as in the museum, almost everything is collected, which makes Kamchatka famous: hot springs and cold rivers, poisonous mud cauldrons and clean lakes full of fish, tundra with berries and birch forest, mountains and swamps, animals and birds. The tourist groups on Uzon are always accompanied by armed hunters - there are simply a large number of bears.
(Fotos from
https://kamchatkaland.ru/note/kaldera-vulkana-uzon)