river in northwestern Colombia. It rises in the western slopes of the Cordillera Occidental of the Andes and flows generally northward to empty into the Gulf of Urabá of the Caribbean Sea. The river is only 416 miles (670 km) long, but its large discharge of no less than 175,000 cubic feet (5,000 cubic m) of water per second transports a very large quantity of sediment that is rapidly filling the gulf. Navigable by small boats as far upstream as Quibdó, the lower Atrato has been considered a feasible route for a transisthmian canal.