Dominating this sea helped free cities like LÃ¼beck, Novgorod, and other Hanseatic towns prosper.
It's not the Mediterranean, but Fernand Braudel highlighted how grain shipments originating from this body of water allowed the Dutch to accumulate Spanish silver. Ships that traveled east [emphasize] towards this body of water were subject to the Sound Toll. An organization based around this body of water set up kontor trading posts, including on river cities like Torun. A ruler chose to build his capital near this sea in order to provide a (*) "window on the West." Dominion over this sea shifted east after the Treaty of Nystad. Monopoly rights of a league organized around this sea were affirmed by the 1370 Treaty of Stralsund, signed by Valdemar IV. Dominating this sea helped free cities like LÃ¼beck, Novgorod, and other Hanseatic towns prosper. For 10 points, Sweden and Russia dueled for domination of what sea? 
It's not the Mediterranean, but Fernand Braudel highlighted how grain shipments originating from this body of water allowed the Dutch to accumulate Spanish silver.
Baltic Sea [accept Gulf of Bothnia or Gulf of Finland specifically] 