Portsmouth is a port in Hampshire, which is a city located in southern England. It is known for being an important Royal navy base and dock. It is mentioned in the excerpt from Equiano’s Interesting Narrative, which revolves around a long journey through different regions in Africa. Thus, in the excerpt, the journey continues from Portsmouth to the Thames. 

"In pursuance of our orders we sailed from Portsmouth for the Thames, and arrived at Deptford the 10th of December, where we cast anchor just as it was high water" (Equiano).