Stillaguamish River: South Fork is a 11 mile trail located near Arlington, WA. The trail is primarily used for canoeing.
Some excellent swimming spots in Arlington like Big Rock, as well as Silvana! Ask any local for directions to some cool spots.
This trip is most often done in tubes and rafts in the summer months, which is how we traveled. You can't exactly put a time limit on the trip as it depends on the speed of the river and the leg of the river you choose to do. Jordan Bridge to River Meadows is a great float but shallow in spots for tube floaters in August. River Meadows Park to Twin Rivers Park is also a good float and in mid-July will accomodate a small boat. The time of year, the water level and the part of the river you float have a huge impact on your trip. We spent 9 hours on the river in early September on a poorly planned float. The earlier in the summer the faster and colder the water, the later in summer the slower... All in all this is always a fun trip for hot days.