Born in the highlands of the State Park of Serra dos Pireneus, the Almas River passes through the center of Pirenopolis and then flows northwest and joins the Araguaia and Tocantins basin. The river becomes strong when it reaches the Belem/Brasilia highway and has many small but treacherous cascades that may have earned it the name "River of Souls" (Rio das Almas). The Almas suffers pollution from the sewers of several towns along its course.