Ft Ebey is partially in the Olympic rain shadow, and has well draining soils, which makes it an excellent winter riding destination. It is adjoining Island County's Kettles Trails Area, and the trails go through both areas.
Read more at the Washington State Parks Page.
Most trails are well drained so there's very little mud. Good ol' fashioned cross country trail riding with roots, rocks, switchbacks and some beautiful forested areas.
The trail system is maintained by the state parks department and the adjacent Kettles Property is managed by Island County.
There are plenty of services and restaurants in nearby Coupeville. Of course the island is home to the famous Penn Cove mussels so don't miss out on a chance for some fresh ones.