No visit to Helsinki, which is by the way a very beautiful and charming capital that too often gets overlooked, would be complete without the short boattrip to Suomenlinna. The harbour is beautiful, and the huge ferries passing by are very impressive as well, and on a sunny day it's surprisingly easy to catch a sunburn there (I speak from experience..) Even though I have to admit that Suomenlinna is not that great and important from a historical point of view, it does offer many interesting things to see and do, and many locals use the place to relax (even though Helsinki isn't really all that stressful). If you like ships, boats, and water in general, Suomenlinna is perfect, as is one of the many boattrips offered that take you around the harbour area.