Thumb Area Bottomland Preserve in Lake Huron off Michigan’s Thumb protects roughly 276 square miles of lakebed and underwater remains near Pointe aux Barques, Harbor Beach, Huron City, and Port Austin. The preserve contains 10 known shipwrecks recorded by the Michigan Department of Environmental Quality, including losses from the era before marine safety services were unified in the United States Coast Guard in 1915. Among them are the package freighters Philadelphia and Albany, which collided and sank off Pointe Aux Barques in 1893. Its importance also includes limestone sea caves and the submerged industrial traces near Grindstone City, making it a notable Great Lakes heritage area.