Visit Ludington’s page on Ludington State Park’s trails says:
The Skyline Trail runs along a tall sand dune ridge, on the south side of the river between the footbridge and Hamlin Dam. The trail begins at the west end of the parking lot and exits onto the Sable River Trail. This trail is completely elevated, made even higher by an extensive wooden boardwalk system. Several vistas let you look out over miles of sand dunes and Lake Michigan. On a clear day, you can see 20 miles to the Silver Lake State Park Sand Dunes. On the back side is an area where you can leave the boardwalk and run up and down the steep slope of this sand dune.