Cotonou is the largest city in Benin. Its official population count was 679,012 inhabitants in 2012; however, over two million people live in …Cotonou is the largest city in Benin. Its official population count was 679,012 inhabitants in 2012; however, over two million people live in the larger urban area. The urban area continues to expand, notably toward the west. The city lies in the southeast of the country, between the Atlantic Ocean and Lake Nokoué.