First Sea was discovered in LY 360 by the settlers of Ship. Its borders are defined by First Land and Near Land, though it also borders First Isle, as well as West Ocean and East Ocean, and fully surrounds Jump Isle. Port villages on First Sea include Ship, Kurok, Shipsister, Jump Village, and Tanq.
First Sea is home to 1,716 merfolk, as of the 905 census. Politically speaking, First Sea is counted as a village, and is included as part of First Nation. However, it contains several merfolk communities, the first and largest of which is New Aquaton, founded in 854. Another community, Neptune's Deep, was founded in 903 to serve as headquarters for the Marine Corps.