Island Center Forest (Vashon DNR)
You are usually guaranteed to run into a horseback rider. Always yield, speak to the horse, and be friendly to the rider.
Info
This is no longer DNR land. It was acquired by King County and as a natural area named Island Center Forest. The parcel is south of Bank Rd. with dozens of miles of singletrack. The parcel is not big, so there is a lot of zigging and zagging, intersections and few TTFs. Muddy areas, sweet rolling slaloms. Woods, and post-logging scotch broom / alder forest. Back when K2 still had manufacturing on the island, these trails were ridden each day at lunch time by K2 dudes.
King County provides some materials on the area: Island Center Forest Map and the King County Parks Site
King County Parks now oversees this section. There is a lot of private property encroaching the edges and so access has become limited. Please review the KC map for where to enter.