Here are a few links which may help to fill in some of the background to sailing in the Baltic:
http://sail-in-finland.info/105-rocks-martin-edges-harbor-pilot-to-finnish-marinas/ is a light-hearted look at sailing mostly in the Turku Archipelago, with details of some natural harbours as well as organised marinas.
https://sail-in-finland.info/2014/02/105-rocks-martin-edges-guide-to-places-to-tie-your-boat-up/ is also by Martin Edge and gives a light-hearted look at sailing in Finland and the Åland Islands.
http://lumpley.com/index.php/anyway/thread/736 deals with saunas and the anxiety they may cause.
http://www.aland.com/en/Travel_and_stay/visitors_marinas/guest_harbours_in_aland covers guest harbours in the Åland Islands.