M-185 is a state trunkline highway in the U.S. state of Michigan that circles Mackinac Island, a popular tourist destination on the Lake Huron side of the Straits of Mackinac, along the island's shoreline. A narrow paved road of 8.004 miles (12.881 km), it offers scenic views of the straits that divide the Upper and the Lower peninsulas of Michigan and Lakes Huron and Michigan. It has no connection to any other Michigan state trunkline highways—as it is on an island—and is accessible only by passenger ferry. The City of Mackinac Island, which shares jurisdiction over the island with the Mackinac Island State Park Commission (MISPC), calls the highway Main Street within the built-up area on the island's southeast quadrant, and Lake Shore Road elsewhere. M-185 passes by several important sites within Mackinac Island State Park, including Fort Mackinac, Arch Rock, British Landing, and Devil's Kitchen.