The Spruce Railroad Trail on the north side of Lake Crescent in the Olympic Peninsula in WA is a fun, if short trail ride with beautiful scenes of the lake all along the way. Start at either end and plan to ride both ways. Take a plunge in the crystal blue waters if you get hot along the way. Keep an eye on the uphill side so as not to miss the railway tunnels that are abandoned. The trail goes around the headlands where the rail tunnels originally cut through the mountainsides. Its a pretty fun excursion if you are in the area.