The Smith River is a river on the Pacific coast of northern California in the United States, approximately 25.1 miles (40.4 km) long. It drains a rugged area of the Pacific Coast Ranges west of the Siskiyou Mountains just south of the Oregon border and north of the watershed of the Klamath River. The catchment area is 719 square miles (1,860 km sq). It is the second largest river system in California that flows freely along its entire course, after the South Fork Trinity River. It was named for the explorer Jedediah Smith.
It is formed by the confluence of its Middle and North forks in Del Norte County, in the extreme northwest corner of California, near the community of Gasquet. The Middle Fork, 27.8 miles (44.7 km) long, rises in Del Norte County, approximately 60 miles (100 km) northeast of Crescent City, and flows west. The North Fork Smith River, 28.1 miles (45.2 km) long, rises in Oregon on the northeast slope of Chetco Peak. The South Fork Smith River enters the Smith River near the community of Berteleda.
The 43.3-mile-long (69.7 km fork rises on the eastern edge of the Smith River National Recreation Area, approximately 30 miles (48 km) east-northeast of Crescent City, flowing southwest and then northwest. From the confluence with the South Fork, the Smith River flows generally northwest, entering the Pacific Ocean near the community of Smith River, approximately 10 miles (16 km) north of Crescent City. Smith River estuary is recognized for protection by the California Bays and Estuaries Policy.