East of Seattle near Enumclaw, the White River / Skookum Flats Loop is a popular 11 mile loop is an extreme singletrack combining the White River Trail (#1199), the Skookum Flats Trail (#1194) and the Dalles River Trail (#1204A). Get ready for rocks, roots and dropoffs. The mountain bike trailhead is located off SR410 at FS7160. Head north on the SFT to FS73. Cross the White River. Head south on the DRT to the WRT. Get ready -- theres over 3,500 feet of vertical.
Overall, Skookum Flats / White River Loop Trail is the 6th most popular mountain bike trail of all 59 mountain biking rides in Washington.