San Cosme is a department of the province of Corrientes, in the northeast of Argentina, which occupies 595 km² in the northwest region of the province. It is bordered on the west by the Capital department, on the south by San Luis del Palmar, on the east by Itatí and on the north by the Republic of Paraguay, from which it is separated by the Paraná river. The head of the department is the homonymous San Cosme. Along with her, Paso de la Patria and Santa Ana de los Guácaras are the other main population centers of the area. According to the 2010 census, 14,141 people lived in the department.
The department includes in the Paraná River the islands: Anteojo, Toledo, Toledita, de los Pájaros, Cambá Acá, de las Ratas and Banco Verde. These last two are exclaves in waters belonging to Paraguay in front of the mouth of the Paraguay River, along with other 4 islands and two sandbanks in the same condition in front of the Paraguayan island Boby Ñú.