From its source near the crest of the Cascades the Rapid River flows southwest and west, collecting numerous headwater tributaries. The Rapid River makes a northward bend. Near the northernmost part of this bend a tributary stream originating in Cup Lake and Saucer Lake and Margaret Lake on the Cascade Crest joins. Soon the North Fork Rapid River joins as well, followed by Meadow Creek. The North Fork rises four miles to the north, its headwaters flowing from Pear Lake, Peach Lake, and Grass Lake, close to Wenatchee Pass on the Cascade crest. Some of the larger mountains in the Rapid River's basin include Valhalla Mountain, Scrabble Mountain, Scorpion Mountain, Sunrise Mountain, Evergreen Mountain, Grizzly Peak, and Fortune Mountain.[3][4]
In terms of river size and streamflow, the true source of the South Fork Skykomish River is the Rapid River and Beckler River, even though the South Fork keeps its name above the Beckler confluence.[5]
^ abGeneral course info mainly from USGS topographic maps accessed via the "GNIS in Google Map" feature of the USGS Geographic Names Information System website.