The Petén department is bordered on the east by Belize and by Mexico (with the Mexican states of Chiapas to the west, Tabasco to the northwest and Campeche to the north). To the south it borders the Guatemalan departments of Alta Verapaz and Izabal. Much of the western border with Mexico is formed by the Usumacinta River and its tributary the Salinas River. Portions of the southern border of the department are formed by the rivers Gracias a Dios and Santa Isabel.