The best switchback climbing practice near Seattle! Love this place. 1100 feet of climbing in 4.2 miles for the entrire loop. Met a friendly guy with a weed wacker clearing the trails and he's trying to get the word out more about this trail system. It's hard to find the trail access points, so I posted a GPX file that has the one behind the office buildings, and another at the south end (which is easy to find from the paved trail).