[Lost Valley Campground - Mid-Michigan, Cabins, Campsites, Marina, Campground Lost Valley Campground is a 55 acre park located on East Twin Lake. Where there is a beautiful sandy beach, and playground for the kids. East Twin Lake welcomes boats of our guest, but at a slow speed, as it is a stocked lake, great for fishing! Here at Lost Valley Campground we have 218 seasonal sites, along with 15 daily camping sites. All sites are equipped with electrical and water hook-up. ]