The longest river in Mexico is the Río Bravo which forms more than half the border with the United States. Almost all Mexican rivers have their source in one of the two principal mountain ranges —the western Sierra Madre or the eastern Sierra Madre— and tend to be short.

Rivers in the west, like the Yaqui or the Lerma, flow into the Pacific Ocean, whilst those in the east, like the Usumacinta and the Pánuco flow into the Gulf of Mexico. In the southern states of Quintana Roo and Yucatán the porous limestone creates underground rivers which flow into the Caribbean Sea. Cenotes are natural wells, formed when the roofs of these rivers collapse. 

Of the many lakes in Mexico, the largest is Chapala, situated between the states of Jalisco and Michoacán. In the state of Chiapas, the Lacandon jungle surrounds the beautiful Agua Azul (blue water) waterfalls of the Usumacinta river.