Most people visit the Askola potholes or devil's churns (hiidenkirnut in Finnish) as a part of a school trip. Me too, but it's been a long time since then. I remembered almost nothing.
This was a nice trip, with Jarmo and his kids. We also went to the bottom of the biggest churn, on very shaky metal ladders.
For those willing to learn more, check out the Askola Hiidenkirnut page on Facebook, on the web, or in Wikipedia.
Photos and videos (c) 2017 by Jari Arkko and Jarmo Ruuth.