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.)
The park has created a fun little video of the Challenge: https://www.youtube.com/watch?time_continue=44&v=Rgec4vPywc0
The route has a Strava segment and any FKTs submitted for a single lap should improve on the current course record on that segment. The GPX file on this page shows three laps of the loop, but the standard FKT route is a single lap.
