On Earth many seas, and they all have names. Only surprising that not all the names match what we see. For example, someone who was on the Black sea, will confirm that it is not black and blue. What is the secret?
Blue Black sea is not always the case. In winter, when blowing cold winds, it frowns, sea surface darkens, crashing down on the shore a huge lead wave. Here and called him Black, which means "dangerous", "severe", "formidable".
But the Yellow sea got its name from the yellow river (the Yellow river). The river flowing into the sea, brings a lot of mud and dirt, causing the sea takes on a muddy yellow color.
There is the White sea. It is Northern, cold, covered in winter white ice. That's why his name is White.
The water in the Red sea is blue. But sometimes on its surface float red algae, and then the water becomes red-brown tint.
There are coral sea, which is called so because it is a huge number of coral reefs.
And even the names of seas are derived from the names of the Islands that are in them: Javanese sea, Japanese, Greenland.
Often the seas assign the names of famous explorers and travelers. For example, there is the Laptev sea, the Bering and Barents seas.