Germany - East Holstein map (DE-318993)

I think I've already told you that I love these German map cards :) They're very informative and immediatelly give you some idea about the region they show. Of course, not everyone likes maps, but I've always been into geography, so I find them really interesting :) Have you known that German name of Baltic Sea was Ostsee, meaning East Sea? I wonder, what's the reason for using absolutely different name than in other languages :)

DE-318993

The sender of this card wrote only that it showed a part of Schleswig Holstein federal state in Germany. There's also no specific information about it on the back side of this card, but after some googleing (or, more precisely, wikipediaing) ;), I found out that it's a map of East Holstein distcrict, including Wagrien peninsula and Fehmarn island.