Почему Балтийское море получило такое название?
Tacitus called it "Mare Suebicum" after the Germanic people of the Suebi, and Ptolemy "Sarmatian Ocean" after the Sarmatians, but the first to name it the "Baltic Sea" ("Mare Balticum") was the eleventh-century German chronicler Adam of Bremen. The origin of the latter name is speculative and it was adopted into Slavic and Finnic languages spoken around the sea, very likely due to the role of Medieval Latin in cartography. It might be connected to the Germanic word "belt", a name used for two of the Danish straits, the Belts, while others claim it to be directly derived from the source of the Germanic word, Latin "balteus" "belt". Adam of Bremen himself compared the sea with a belt, stating that it is so named because it stretches through the land as a belt ("Balticus, eo quod in modum baltei longo tractu per Scithicas regiones tendatur usque in Greciam").
because it stretches through the land as a belt