1) Impact crater of Finland 
Lumparn (fi. Lumpari) is a large bay devoid of islands in the Main Island of Åland, Finland, bordered by Sund to the north, Lumparland to the east, Lemland to the south and Jomala to the west. Most of the bay fills a nine kilometer wide impact crater. The crater is estimated to be about 1000 million years old (Proterozoic). The depression was ori...