Final answer:
Poland is the country with the Gulf of Gdansk and the Bay of Pomerania on the Baltic Sea, both of which are vital for the nation's access to maritime trade and economy.
Step-by-step explanation:
The country with the Gulf of Gdansk on the northern coast, and the Bay of Pomerania on the Baltic Sea is Poland. The Gulf of Gdansk is situated at Poland's northern border and is an important part of the country's access to the sea, which was guaranteed after World War I, specifically through the creation of the Polish Corridor as mentioned in the Treaty of Versailles. This corridor was a significant geographical feature, as it provided Poland with a much-needed opening to the Baltic Sea while also separating parts of Germany.
Meanwhile, the Bay of Pomerania is bounded by the Pomeranian coast of Poland and the islands of Usedom and Wolin. It serves as another crucial maritime area for Poland, contributing to its economy and trade. These regions gained particular significance after the re-establishment of Poland post World War I, as the country needed these coastal zones to support its maritime and economic development.