Cougar Mountain has seen lots of history over the years, and some remnants of it remain in the form of logging roads, mining railway beds, mine shafts, and the old Nike missile site. Aside from that, it's also a peaceful wildlife area amid the suburban eastside bustle, criss-crossed with trails of various sizes and slopes. The park is a favorite for groups and families that want to get out in the wilderness and see some history, but not travel too far.
Some trails are restricted to hikers only, so pay attention to signs; however, equestrian trails loop their way throughout the park, so you won't miss much territory. It's particularly important to stay on the maintained trails, though, as sinkholes from old mine shafts are continually forming in this area, and the weight of a horse could make the difference. Warning signs tell about existing dangers, and should be taken seriously.
There are officially three trailheads that are open to equestrian use, but the Red Town Trailhead parking doesn' t have much room for horse trailers, so only the Sky Country and Anti-Aircraft Peak trailheads are listed below. The Sky Country trailhead has the most trailer space.
Open
To Sky Country Trailhead: From I-90, take Exit 13 and drive south on Lakemont Blvd SE for 2.5 miles. Turn left on SE Cougar Mountain Way and then right on 166th Way SE (the main road will veer left at this point with a big left-pointing arrow sign which makes a good landmark). Follow 166th to the gate at its end (0.7 mi). On the right is the Sky Country Trailhead parking lot; follow the signs for the horse trailer parking area at the back.
To Anti-Aircraft Peak Trailhead: From I-90, take Exit 13 and drive south on Lakemont Blvd SE for 2.5 miles. Turn left onto SE Cougar Mountain Way. Follow the double yellow line (the road will first swing left and become 168th Pl SE and then right to become SE 60th St). Turn off 60th St uphill onto the dead end road, SE Cougar Mountain Dr. The road will change to gravel - at the end is the trailhead. Trailer parking is a gravel lot on the left across from the turn into the car parking lot. Watch for pedestrians & other trail users on the last mile of this road.
Length: 12 miles of equestrian trails (more for hikers)
Surface: dirt, gravel. Some sections can be muddy after rainy weather. Some steep parts, particularly to the east.
Share with: hikers, joggers, family groups
Restrooms and picnic tables at Anti-Aircraft Peak Trailhead.
Parking for: At Sky Country
Trailhead, 10+ trailers. At Anti-Aircraft Peak Trailhead, 4-5
trailers depending on how people park.
King County Parks:
Park website
Trail website
King Cty map (.PDF, 5.9 Mb):
http://your.kingcounty.gov/ftp/gis/Web/VMC/recreation/CM-bw_2009.pdf
King County Parks has added a downloadable "brochure" (including a map) for this park to their "Backcountry Trails Map Brochure Series."
Another map (does not show all trails, but smaller download):
http://pwckitsap.org/downloads/cougar_mountain.pdf