Final answer:
The river delta that is formed as water enters the Baltic Sea is called the Vistula River Delta.
Step-by-step explanation:
The river delta that is formed as water enters the Baltic Sea is called the Vistula River Delta. The Vistula River is the longest river in Poland and it flows into the Baltic Sea, forming a delta at its mouth. The Vistula River Delta is an important wetland area and provides habitat for various species of plants and animals.