De Tour Passage Underwater Preserve protects Michigan waters in Lake Huron around Drummond Island, including all of DeTour Passage and nearby parts of Lake Huron and the St. Marys River. The area became vital to Great Lakes shipping as hematite mining grew in northern Minnesota in the late 19th century and steel production expanded around Cleveland, Detroit, and Gary. Nearly all commercial traffic entering or leaving Lake Superior passes through this narrow route, and ships also stopped at Drummond Island for quarry products. Heavy traffic, storms, rough seas, and difficult navigation left the preserve rich in Lake freighter wrecks, many in shallow water accessible to divers.