The Sehome Hill Arboretum (or, 'the arb,' as people call it on campus) is quite literally in my back yard.
The arboretum features dozens of miles of light hiking trails - most on the west side of Arboretum Drive are mapped out, but there's a whole bunch of others on the east side that aren't mapped. The lower west side trails are frequently used by students as a means of getting to class, and as a hideout for smoking - try the east side ones for a bit more solitude.
While not the most exciting hiking spot, the arb is a great place for locals to get a bit of exercise, walk the dogs, and take young ones exploring. You'll find all sorts of man-made treasures in the woods, like cute little bird houses or tiny mirror art.
To no avail, I spent about 2 hours today searching for a supposedly-hidden rope swing somewhere deep in the trees.