On the Kamchatka peninsula, there are plenty of active volcanos, and one volcano’s slope – on the Tolbachik volcano – there is the river Studenaia, which is known for its riverbed being canyons inside the mountain. During the first part of the day in the “dry” season one can easily take a walk through them. Let’s take a look:
This is the Tolbachik volcano.
So it’s a tourist attraction and a magnet.
Thanks to Shpilenok and others for the photos!