The German submarines could not come into gulf of Finland. Because there was a terrifying quantity of mines. Destruction - 100 %.
There were german subs in Helsinki.
There was an old rusty buoy at my yacht club in Helsinki, they said it was old german submarine buoy. Link to german subs in the gulf of finland.
http://users.tkk.fi/jaromaa/Navygall...anne-boats.htm
maybe someone vant to do badewanne-boats campaign.