Only opened in May 2016, Vallisaari is a true treasure right in front of Helsinki’s coastline. The fairly big island was in use under the military until pretty much then, but finally opened up for visitors as well. The island combines history and nature beautifully with stunning views of the city from high above – for me the perfect alternative day trip for those seeking to avoid the crowds heading out to Suomenlinna in the summer, the season ends in late September.