Go to ebay, look for u.s. treasure atlas #5. There is a ton of material about michigan; more than you could search in a lifetime. I know because massachusetts is in that same book. I would love to tell you some, but it's copyrighted. Just remember, these are just leads that require more research, and these books were written in 1985, so it may have been found already i.e.- the wreck of the wyhdah off cape cod is in this book, and it was located in 1986. I hope this helps, and good luck!
I am just a little South of The Bridge. I have the #5 Treasure Atlas. It is interesting, but I can't say it will help me much on day to day treasure hunting.
You will find many people on here, and on the Michigan Forum with tips, and locations to hunt etc.
And watch for posts from Gypsy Heart, she seems to be the world's best researcher!