Germany–Poland border

The Oder ( ; Czech and ) is a river in Central Europe. It is Poland's second-longest river and third-longest within its borders after the Vistula and its largest tributary the Warta. The Oder rises in the Czech Republic and flows through western Poland, later forming of the border between Poland and Germany as part of the Oder–Neisse line. The river ultimately flows into the Szczecin Lagoon north of Szczecin and then into three branches (the Dziwna, Świna and Peene) that empty into the Bay of Pomerania of the Baltic Sea.

river in Central Europe

estuary on the Polish-German border

Basin in the Baltic Sea

treaty

international border

1990 state treaty that governs the borders between Germany and Poland

1950 treaty between Poland and East Germany

1939 German special forces operation against Poland prior to World War II

battles that occurred in the first days of the Nazi Germany invasion of Poland in September 1939