The Skykomish (wiping the coke off the screen that blew out my nose when I read this post) flows out of the Cascades eventually joining the Snoqulamie and forming the Snohomish River. The Snohomish drains into Puget Sound just North of Everett.

If you cross the Railroad tracks at Index you can accesses a pretty good portion of the upper river. There is also some access where the Wallace River comes in as well as the Sultan.

Now if you had a boat ...