OK, so it's a hole in the ground, but it's Europe's deepest, at 23m, with a diameter of 14m, and mystery surrounds its origins (glacial erosion or a natural-gas blow-out are the most plausible theories). You can descend a metal staircase into the cavity or view it from the 21m-high observation tower. Pirunpesä is 52km south of Seinäjoki (there's no public transport). Take Rd 19 to the Jalasjärvi exit then head southeast for 16km; it's on your right.
