Castro Marim (Portuguese pronunciation: [ˈkaʃtɾu mɐˈɾĩ]) is a town and a municipality in the southern region of Algarve, in Portugal. The municipality is composed of 4 parishes. The present Mayor is José Fernandes Estevens, elected by the Social Democratic Party. The municipal holiday is June 24. In the Roman era, Castro Marim was known as Aesuris.