Guyana borders Argentina.
Argentina ( [ ɑrdʒənˈtiːnə ] [ aɾxenˈtina ] ) , officially the Argentine Republic ( República Argentina ) , is a federal republic in the southern portion of South America . Guyana ( pronounced [ ɡaɪˈɑːnə ] or [ ɡaɪˈænə ] ) , officially the Co-operative Republic of Guyana , is a sovereign state on the northern mainland of South America . Uruguay . It borders Argentina to its west and Brazil to its north and east , with the Río de la Plata ( River of Silver ) to the south and the Atlantic Ocean to the southeast .