Marin joulukalenteri, 7th door

We Finns count down the 24 days before Christmas by using Advent Calendars.
I haven't got one for myself this year, so I decided open my own Advent Calendar here in Blip.
So today I open another door of Marin Joulukalenteri:

Ice conditions in the Baltic Sea vary a lot from one year to another. The Bay of Bothnia and the eastern Gulf of Finland gets an ice cover every year. In mild winters the Sea of Bothnia doesn't freeze at all and the Gulf of Finland only gets a partial ice cover. In normal winters the ice gets to cover also the rest of the Sea of Bothnia, the Archipelago Sea, the whole Gulf of Finland and parts of the northern Baltic Proper.
In the beginning of the winter it is impossible to predict the ice conditions of the coming ice winter. Any reliable prediction can not be made before the end of January.

At the moment sea water is 3-6C degrees, so no sea ice for a while if weather stays so warm.I'm just thinking that it would not be so Christmassy to get the tree with rowing boat ;)