San Antonio is a Chilean port city, commune, and the capital of the San Antonio Province in the Valparaíso Region. Situated on hills and coastal dunes north of the Maipo River's mouth, it is divided by the Arévalo and El Sauce estuaries. The city borders Cartagena to the north, Melipilla and Santo Domingo to the east and south, and the Pacific Ocean to the west, covering an area of 502.