The Hoko River is a river in the U.S. state of Washington. It originates in the foothills of the Olympic Mountains, and runs about 25 miles (40 km) to the Pacific Ocean through a rugged landscape that has been heavily logged. Its largest tributary is the Little Hoko River, which joins at river mile 3.5-mile (5.6 km). The lower 1 mile (1.6 km) of the Hoko River is estuarine.