The Río San Pedro is a river of Guatemala and Mexico. Its sources are located in the Guatemalan department of El Petén at 17.134803°N 89.902668°W (Río San Pedro). The river flows westwards until it reaches the Mexican border and crosses into the state of Tabasco at 17.279636°N 90.987697°W (Río San Pedro). From there it continues northwest and joins the Usumacinta River.