Esroniet is an island-nation that lies in between Tamriel and Akavir. It was conquered by Uriel Septim V and the Expeditionary Force in 3E 284. It is believed that the island is located somewhere in the middle of the vast Padomaic Ocean.
Black Harbor is a port city on Esroniet that was conquered by Uriel Septim V in 3E 282, two years before the island-nation was conquered. In 3E 284 the island's ruler, Prince Bashomon, surrendered the entire kingdom to Uriel Septim V, then he transformed it into a major base for the Imperial Navy and used it as a launching point for the invasion of Akavir in 3E 288.