The Tinayguk River is a 44-mile (71 km) tributary of the North Fork Koyukuk River in the U.S. state of Alaska. Heading in the Endicott Mountains of the Brooks Range, the river flows generally west then south to meet the larger river about 80 miles (130 km) north of Bettles. In 1980, the entire river was designated "wild" and added to the National Wild and Scenic Rivers System. The designation means that the Tinayguk is unpolluted, free-flowing and generally inaccessible except by trail and that its watershed is essentially primitive.