Barbarossa Sea is the first sea in Crown Port. It's where you began here. It's the main source of Sailing Treasure T1, Black Iron Ore, Red Pine and Thick Hide. You need these for upgrading your Crown Port from level 1 to 21 and the technology from level 1 to 5. After completing exploring the Large Animal Herd, you can go to Blue Coast. Note: you can click and drag the screen of the sea to see the second part of the map shown in the picture at the right.
Every exploration costs 200 Gold.