At the edge of Myössäjärvi, 16km south of Inari, look out for the Karhunpesäkivi rest stop. From here, a 300m timber boardwalk (mainly comprising steps) leads through the forest to Finland's largest tafone (cave-like formation found in granular rock), the only one in the world known to have shifted from its original base during the last ice age. You can enter the hollow boulder; although you have to crawl to enter, the honeycomb-like structure is high enough to stand upright.