Bay, northern section of Gulf of Guinea .
It extends along the West African coast about 400 mi (640 km) from Cape St. Paul, Ghana, past Togo and Benin to an outlet of the Niger River in Nigeria. Major ports include Lomé , Cotonou , and Lagos . It was the scene of extensive slave trading during the 16th–19th century, and the region of coastal lagoons west of the Niger delta became known as the Slave Coast. By the 1830s trade in palm oil had become the major economic activity. Petroleum was discovered in the Niger delta in the 1950s.