Vistula Lagoon of the Ests". Over three hundred years later, in the first half of the 13th Century, the name of Vistula Lagoon occurs in deeds issued by Teutonic Order in Latin version as Mare Recens (1246 - "mare" - a pool or lake or sea and "recens" - fresh) in contrast to the contemporary name for the Baltic Sea - Mare Salsum (Salty Sea). Then in 1251 we find record about Mare Recens et Neriam (Frisches Haff and Frische Nehrung, now Vistula Spit) and finally in 1288 Recenti Mari Hab (Haff) which as one can see corresponds with later German "Frisches
Vistula Lagoon Century as Estmere. It is an Anglo-Saxon translation of Old Prussian name for the lagoon - *Aīstinmari (modern Lithuanian - Aistmarės) derived from (OP - Old Prussian) Aistei - "Ests", (LAT - Latin)"Aestii" etc. and (OP) *mari - "lagoon (a body of water cut off from a larger body by a reef of sand), fresh water bay". The Ests were Baltic people who since 9th Century became called in some historical sources (first time by Bavarian Geographer) Bruzi, Pruzzen, Pruteni etc. - Old Prussians. So the oldest known meaning of the name of Vistula Lagoon was "The lagoon or sea