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 .