I was playing about with Google Earth and looking at some imagery of Finland (as you do) and I noticed these weird circular shaped "holes" (for want of a better word) in the distribution of the Åland islands. For scale, they are each about 3km in diameter and about 16km apart.
It's really strange the way it looks like there's a huge lens over each of these points, distorting the surrounding islands into sort-of circular shapes.
I'm quite mystified about what could have caused these. I can't imagine what sort of volcanic activity could have had that effect (volcanos tend to create mountains, not lakes) so I'm guessing that they must be impact craters. But I can't find them on any lists of Finnish impact craters. Also, it seems highly unlikely for there to be two similarly-sized craters so close together (unless a single meteor broke into two before impact, or they are of very different ages and the local geography happens to be very good at preserving impact craters of this sort of size).
This isn't an April fool joke - see for yourself.