High Quality Content by WIKIPEDIA articles! The Hoh River is a river in the U.S. state of Washington, located on the Olympic Peninsula. About 56 miles (90 km) long, the Hoh River originates at the Hoh Glacier on Mount Olympus and flows west through the Olympic Mountains of Olympic National Park and Olympic National Forest, then through the foothills in a broad valley, emptying into the Pacific Ocean at the Hoh Indian Reservation. The final portion of the Hoh River`s course marks the boundary between the coastal segment of Olympic National Park and Olympic National Forest, the Hoh Indian Reservation.