The Inner Sea is one of the most heavily traveled and populated bodies of water in Golarion. Formed when the Starstone fell to earth in -5293 AR, reshaping the face of the planet, the Inner Sea rests between Avistan and Garund. Before Earthfall, the two continents had been joined by a land bridge. The impact collapsed the connection, allowing water from the Arcadian Ocean to flow in. The sea is now separated from the Arcadian Ocean by the Hespereth Strait and the Arch of Aroden, which is currently under Chelaxian control. To the east it connects to the Obari Ocean between the nations of Osirion and Qadira.
The Inner Sea is a cradle of the human race, and six of the most powerful nations on Golarion—Absalom, Andoran, Cheliax, Osirion, Qadira, and Taldor—lie on its shores. Naval battles between these emerging world powers are commonplace. There is abundant life beneath the waves as well, including societies of cecaelias, gillmen, locathahs, merfolk, and tritons, as well as monsters like aboleths, devilfish, and grindylows.