The Samish River is approximately 25 miles (40 km) long, in northwestern Washington in the United States. The river drains an area of 139 square miles (360 km2) between the Skagit River basin on the south and the Nooksack River basin on the north. The Samish River originates on a low divide in Whatcom County, and its tributary, Friday Creek, originates in the hills south of Bellingham. The river continues its southwesterly flow through Skagit County and outlets into Samish Bay in Puget Sound.