Coatzacoalcos River (ko-aht-sah-ko-AHL-kos), c.175 mi/282 km long, in Oaxaca and Veracruz, SE Mexico, the most important river of the Isthmus of Tehuantepec; rises in headstreams in Sierra Madre del Sur N of Ciudad Ixtepec; flows NNE in meandering course, past Minatitlán, to Gulf of Campeche at Coatzacoalos. Navigable 125 mi/201 km. Its lower course was early explored by Cortés.
