This short, fun route is in Indiana Dunes State Park:

"Challenge yourself, your friends and your family to climb the three tallest sand dunes at Indiana Dunes State Park. The 1.5-mile challenge trail is the toughest in the park, with 552 vertical feet to climb. The reward: breathtaking views and the title of dune conqueror." (Based on multiple GPS activities on this route, the total vert appears to be less than the 552 stated by State Parks.)

Luke Distelhorst submitted the route:

Circumnavigation of Galcier Peak, 107 miles: White River to Boulder Pass trail to the Napeequa, Little Giant Pass to the Chiwawa River, Chiwawa River road and Phelps Creek to Spider Gap and Lyman Lakes, Cloudy Pass to Suiattle Pass and the Pacific Crest Trail, PCT southbound to Indian Pass and return to White River via Indian Creek.