Welcome to Portland's second creepiest park (after Kelley Butte, of course). Marshy badlands surround an ancient woodland harboring an unnameable evil. Possibly. Personally, I wouldn't bring children here (again), unless they really liked climbing on rocks and weren't of a sensitive disposition.
All year / whatever.
If you find any factual innaccuracies in this post, please email me via richard at thingstodoinportland dot org so I can fix it for everyone. Thanks in advance!
Trailhead at 19th Avenue and Sparrow Street, Milwaukie [Google map].