Deep River is a census-designated place (CDP) in Wahkiakum County, Washington, northwest of the town of Cathlamet and east of the city of Long Beach.

As of the census of 2010,[1] there were 204 people, 92 households, and 63 families residing in the CDP.

25.0% of all households were made up of individuals, and 10.7% had someone living alone who was 65 years of age or older.

94.6% of Deep Riverians have graduated from high school or higher.

Krist Novoselic, the bassist for early 1990s grunge rock band, Nirvana, was recorded as being a resident of Deep River.