South Tiger Mountain is the easiest of a trio of peaks in the Tiger Mountain State Forest near Issaquah, Washington.
(Note of August 2018 - temporary closure of South Tiger Traverse - access from the north is still possible.)
I-90 Exit 25 for Highway 18 is the easiest way to reach the trailhead parking area. I've used the upper parking lot for two activations here - note that a Washington State Discovery Pass is required. There is an unattractive toilet at the upper parking lot.