The Skykomish River is an extremely popular rafting place during the peak snowmelt period from mid-March to mid-July. The upper portion of the “Sky” from Skykomish  to Baring and the South Fork from Skykomish to Index  are not for beginners.
The famous “Boulder Drop” section is class IV+ water, and there are many other deep plunges and vertical drops of class IV. The various commercial rafting companies recommend that anyone running the upper Skykomish have previous rafting experience and be in good physical condition.
Trips are available on most early summer weekends, with fewer weekday runs. Some companies restrict Skykomish rafting to those at least 16 years old.
Based in Index , Chinook Expeditions (800/241-3451, www.chinookexpeditions.com ) runs excellent float and white-water trips, including a six-day Cascade loop trip (May–July, $865) that includes runs down the Skagit, Skykomish, Methow, and Wenatchee rivers. Chinook also offers Skykomish trips ($79) in the fall months when conditions are fast and wild.
Wave Trek (206/793-1705 or 800/543-7971, www.wavetrek.com , $85) is an Index-based rafting and kayaking company with trips down both the main fork of the Sky, and the wild North Fork. They also teach multi-day kayaking classes for those who want to take a bigger step into river-running.
For a do-it-yourself trip, the lower Skykomish is a peaceful river to raft or kayak, with a few small, generally avoidable, rapids above Sultan. It’s rated class II+ from Big Eddy State Park (a.k.a. Sky River State Scenic Park, two miles east of Gold Bar where Highway 2 crosses the river) to Sultan, and class I from Sultan  to Monroe .