Has anyone visited the Suomenlinna UNESCO fortress in Helsinki in December? Is it open? I wonder if the ferry still operates when it’s minus degrees and there’s a lot of snow.
Check out here.
http://www.suomenlinna.fi/en/opening-hours/
It says on 24th and 25th of December everything is closed, but I don't know if that means public access to Suomenlinna is denied. But apart from exceptions, it is still operating in December. Of course, beyond September some attractions are closed or operate shorter times.