“A paved Pathway connecting Blythe Park to Marymoor Park that takes you along the Sammamish River.
— Tony Locati
A paved trail starting at Blythe Park in Bothell and ending at Marymoor Park in Redmond is a very flat, well maintained path along the Sammamish River. From Blythe Park, it's an extension of the Burke Gilman trail that is part of the Lake Washington 60 mile loop.
Attractions along the way include Redhook Brewery at the halfway point. The section of this paved path starting just before Redhook and ending as you enter Redmond also has a singletrack (actually its a horse trail, but typically used by trail runners and mountain bikers) if you prefer to stay off the pavement. This is also the section of the Sammamish River trail that connects the Tolt Pipeline doubletrack trail to the Puget Power-line singletrack trail.
For those wanting to continue on after Marymoor, you have a choice of either following the paved trail East through Marymoor park at to the East Sammamish trail or East Lake Sammamish road that has a nice bike lane all the way to Issaquah, or not entering Marymoor and following the road West Lake Sammamish and make a loop around Lake Sammamish.
This trail is very well-used and can become quite busy on the weekends.