Lagos Lagoon is a lagoon found in the city of Lagos, southwest Nigeria, the most populous city in Africa. The name Lagos means 'lakes' in Portuguese, therefore Lagos Lagoon is an example of a tautological place name. The lagoon lies between the Atlantic Ocean and Lagos State. It is one of the ten lagoons in Lagos State and the largest in the Gulf of Guinea which spans over 6,000 square kilometers (2,300 sq mi).