Located just west of Traverse City Michigan, about 7.5 hours from Indy. The island is only open to backpackers, and on a non-holiday weekend, you will be about one of 10-20 people on the island. This trip will require a Friday off due to the ferry schedule. This place has something for everyone. There are 20 miles of sandy beaches, a secluded inland lake, 25 miles of trails, old homesteads, eagles, plovers, dunes, an old apple orchard.
We'll be departing for Michigan Thursday evening. We have to be at the dock at 9am to register and purchase ferry tickets ($32). We'll be spending Friday night and Saturday night on the island. On Sunday morning we'll take the ferry back to the mainland.
Wikipedia page about park
If there are any comments, suggestions, or questions you can post them in the comment section below or send me an email.