The Balsas River is a river in south-central Mexico which forms a large basin called the Balsas Basin. At 771 kilometres long it is one of Mexico's longest rivers. River upstream of an Australian trout farm A river is a large natural waterway. ...

The river originates at the confluence of the San Martin and Zahuapan Rivers in the state of Puebla. From there it flows southwestward and then westward through the state of Guerrero. It forms the border between Guerrero and the state of Michoacán and reaches the Pacific Ocean at Mongrove Point, adjacent to the city of Lázaro Cárdenas, Michoacán. The Mexican state of Puebla is located in the center of the country, to the east of Mexico City. ... Guerrero is a state in the United Mexican States. ... Guerrero is a state in the United Mexican States. ... Michoacán de Ocampo (From michamacuan, Nahuatl for the place of the fishermen) is one of the 31 constituent states of Mexico. ... Lázaro Cárdenas is a town located in the southern part of the state of Michoacán, it was formerly known as Los Llanitos, but it change its name for the one of Lázaro Cárdenas who was president of Mexico from 1934 to 1940. ...

Along its length it has a number of different names; in its initial stretches it is known as the Atoyac River; within Guerrero is it known locally as the Mezcala.

There are many rapids along its length. The river is used to generate hydroelectric power. It is also a source of water for irrigation.