No.

Because all the seas in the world are connected, they are all salty water, there is no real freshwater sea. In western Europe, there is an inland sea called the Baltic Sea, which is the sea with the lowest salinity in the world. Its salt content is only 7-8‰, which is lower than the average concentration of about 35‰ in the world's seawater. It can be drunk directly. Its main causes: there are a large number of rivers (fresh water) injected along the coast, low temperature and small evaporation, and less water exchange with the open sea.

No, there are only seas with relatively low salinity.

There is no freshwater sea, only freshwater lakes.

The closed seas near the mouths of larger rivers may form sea areas with abnormally low salinity. For example, the salinity of the Baltic Sea is only about 10 thousandths all year round, which is only one-tenth of the average level of the world's oceans. The Amazon River and the Congo River, the big rivers in the equatorial region, can also wash out 100-200 kilometers of freshwater tongues in the estuary sea area. Even during the great flood of 1998, the sea area from the Yangtze River estuary to Zhoushan Islands almost became fresh water.

Yes, the largest freshwater sea is the Baltic Sea, located in the north of Europe.

The Baltic Sea has ferries connecting major ports of coastal countries. It is connected to the White Sea through the White Sea-Baltic Canal and to the Volga River through the Lenin Volga-Baltic Waterway.

Baltic Sea.

Because the average salt content of the Baltic Sea is only 0.7%-0.8%, which is lower than the 0.9% salt content of physiological saline, it can be drunk directly and belongs to brackish water or fresh water in a broad sense. Therefore, the Baltic Sea can barely be regarded as a freshwater sea.