The Saint Joe River (sometimes abbreviated St. Joe River) is a long tributary of Coeur d'Alene Lake in northern Idaho. Beginning at an elevation of in the Northern Bitterroot Range of eastern Shoshone County, it flows generally west through the Saint Joe River Valley and the communities of Avery and Calder. Past Calder, it flows into Benewah County and through the town of St. Maries, where it receives its largest tributary, the Saint Maries River. It then turns northwest, passing through Heyburn State Park before reaching its mouth just north of the Kootenai County line. Much of the river's route through Heyburn State Park is partially flooded due to raised water levels from Post Falls Dam on the Spokane River below Coeur d'Alene Lake. With a mouth elevation of , it has been described as the highest navigable river in the world.