The Skykomish River is a Washington river which drains the west side of the Cascade Mountains in the southeast section of Snohomish County and the northeast corner of King County. The river starts with the confluence of the North Fork Skykomish River and South Fork Skykomish River approximately one mile west of Index, then flowing northwesterly towards Puget Sound. It is joined by the Sultan River and the Wallace River at Sultan. It then meets the Snoqualmie River to form the Snohomish River at Monroe. The Snohomish River continues along the river valley eventually dumping into Port Gardner Bay on Possession Sound .
The Skykomish River's main stem is 29 miles (47 km) long. The length including its headwater tributaries, South Fork Skykomish and Tye River, is 62.4 miles (100 km). The Skykomish's drainage basin is 834 square miles (2,160 km2) in area. The headwaters of the North Fork Skykomish River are located in the Henry M. Jackson Wilderness near Dishpan Gap along the Pacific Crest Trail. It flows as a small stream off the north slope of Skykomish Peak.
The South Fork Skykomish River begins at the confluence of the Tye River and the Foss River, to the east of Skykomish. From the confluence the South Fork flows northwest. Near the eastern boundary of the city of Skykomish, the Beckler River joins it. To the west of the city of Skykomish, the Miller River joins it. Shortly before converging with the North Fork the river drops over Eagle Falls, followed by Canyon Falls and then, finally, Sunset Falls before its confluence with the North Fork.