Fort Ebey State park is looked just north of Coupville, WA on Whidbey Island, just off State Hwy 20. This is a great trail system with about 35 miles of mostly single track with some connector trails that are double. These trails have all levels of riding from easy beginner gravel trails to difficult single track runs. The difficult trails include steep climbs, fast downhills and technical obstacles with tight switch backs. The trail system is shared with hikers throughout and horses on the east side of the park that is not state property. If your riding on the West side of the park, you will need a discover pass.
I got the chance to ride all the trails within the system over a few months. I highly recommend bringing a map of the trail system on the first couple rides, until you get familiar with the trails. Click here for a trail map to print out. I found that parking right off Hwy 20 is free and much easier. Headed North on 20, about 3 miles out of Coupeville, the first gate parking is at the Kettles trail head on the left side of the street. From there I really found a really good loop that I liked to ride. Here is the list of trails by order that made a really nice flow.
Humpty Dumpty - Hot UMSC - Hot Navy - Humpty Dumpty - Whippersnapper - Escape - Kettles - Cedar Ridge - Cedar Hollow - Bluff - Hokey Ko Dodo - Kettles - Forest Run - Campground - Woodpecker Haven - Brave Heart - Raider Creek - Full Loop of Shepherds Crook - Princess Run - Pigeon Ridge - Main Line - The Tunnel - Emily's Ridge - Fisher Ridge - Hugh's Delight and with the high amount of trails that are packed toward the end you can pick and choose what you want to ride on your way back to the Kettles Trail Head. My three favorite trails in this system are all the Hot UMSC/Navy trails, Cedar Ridge/Hollow, and whipper snapper trail.
If you have the opportunity I would highly recommend this trail if your in the area. It was really nicely marked unlike some of the other trail systems in Washington. It is easy to get to, the eastside is free to ride and offers several trails that are not on the map. Before I left, they put in several new large maps throughout the park with all the new trails.