Mexico is a country of exceptional physiographic diversity, and the heterogeneity of surface- water resources in the country is remarkable. Some of the wettest (e.g., the Lacandón Forest in Chiapas) and driest (e.g., the deserts of Sonora) places on the North American continent are in Mexico. Mexico is also home to a great diversity of indigenous cultures, many of which have long and complex relationships with rivers and streams. In this chapter, we describe eight rivers: Río Fuerte, Río Salado, Río Nazas-Aguanaval, Río Tamesí, Río Balsas, Río De la Sierra, Río Lacantún, and Río Hondo. The basins we selected are distributed throughout the country and have diverse drainage patterns; some are endorheic, and others drain into the Pacific Ocean, the Gulf of Mexico, or the Caribbean Sea.