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The Hoh River is a river of the Pacific Northwest, located on the Olympic Peninsula in the U.S. state of Washington. About 56 miles (90 km) long, the Hoh River originates at the snout of Hoh Glacier on Mount Olympus and flows westward through the Olympic Mountains of Olympic National Park and Olympic National Forest, then through 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 south coastal segment of Olympic National Park and the Hoh Indian Reservation.

The Hoh's drainage basin is 299 square miles (770 km²). Its discharge, or streamflow, has considerable seasonal variation, with summer flow averaging about one-third that of winter flows.

The Hoh is a glacial river fed by glaciers on Mount Olympus, such as the Blue Glacier. The glaciers grind rock into a fine glacial flour which turns the Hoh River a milky slate blue color. The river valley is generally broad and relatively flat, causing the glacial sediments to settle out, creating extensive gravel bars, river meanders, and the many side channels characteristic of a braided river.

One of the road entrances to Olympic National Park exits from Olympic Highway 101 twelve miles south of Forks, WA and follows the north bank of Hoh River upstream to the Hoh Rain Forest Visitor Center, campground, and the trailhead for the Hoh River Trail. This hiking trail follows the river 12 miles through the Hoh Rain Forest to the base of Mount Olympus, and then continues to climb steeply another 6 miles to Glacier Meadows campsite, and the start of the primary climbing route for Mount Olympus. Logjams in the river channel are common, resulting in quiet pools and new river braids being formed.

The river's name and the name of the Hoh tribe both ultimately come from the Quinault placename /húx^w/.