Other (rare) synonyms of the baltic-sea include:
Thank you for the heads-up. Tags were merged and synonym added. I have not added the other synonyms yet. I would rather wait to see if anyone actually creates those tags. The reason being that as of now we have 3 questions tagged baltic-sea which seems to show that it's not a hot topic for Travel. This means that the likelihood of new questions with new tags being asked is quite low.