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."
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.