Sugar Company factories in the Thumb region. The sugar companies were organized with money from lumber barons such as Rasmus Hanson. St. Clair boasts the world's largest boardwalk along freshwater, the St. Clair River. Turnip Rock, an unusual undercut sea stack at the extreme northern tip of the Thumb. Michigan Underwater Preserves are protected areas of the Great Lakes on Michigan's coast. There are nineteen major shipwrecks in the of the Thumb Area Bottomland Preserve and the Sanilac Shores Underwater Preserve which expands a total of of Lake Huron. Caseville is the home of the annual Cheeseburger in Caseville festival, a hometown festival devoted to Jimmy Buffett's song "Cheeseburger in Paradise". Traveling around the Thumb A favorite of tourists who visit this area is traveling the Lake Huron and Saginaw Bay shoreline via M-25 (formerly US Highway 25 until 1973). M-25 starts at the end of I-69/I-94 in Port Huron at the foot of the Blue Water Bridge and ends in Bay City. The whole highway is about , and passes through quaint cities and villages. Located along Lake Huron through which M-25 passes are five lighthouses: Fort Gratiot Lighthouse, Port Sanilac lighthouse, Pointe aux Barques Lighthouse, Harbor Beach Light, and the Port Austin Lighthouse. The Great Lakes Circle Tour is a designated scenic road system connecting all of the Great Lakes and the St. Lawrence River. Many visitors choose to begin the circle tour in Port Huron, from which they can circle Lake Huron. M-25 winds around the Thumb and along the Saginaw Bay to Saginaw and Bay City. Lexington and Port Austin feature beaches and boardwalks that are favorites with visitors. Lighthouse Tour In order from east to west: Huron Lightship — Lake Huron / St. Clair River — Port Huron Fort Gratiot Light—Lake Huron / St. Clair River—Port Huron Port Sanilac Light—Lake Huron— Port Sanilac—Private White Rock Memorial Light—Lake Huron — White Rock—Private Harbor Beach Light—Lake Huron — Harbor Beach Pointe aux Barques Light—Lake Huron—near Port Hope Port Austin Light—Lake Huron — Port Austin Charity Island Light — Saginaw Bay Saginaw River Light — Saginaw River Area festivals and events Antique and Yard Sale Trail 2nd weekend in August, (Algonac to Sebewaing) Art on the River, third week in June, St. Clair. Art on the Avenue, downtown Port Huron, 3rd week in August. around the state. Bay Port Fish Sandwich Festival (Bay Port) Blue Water Ramble (St.