Straits of Mackinac

Diving here is done from day boats on both sides of the Mackinac Bridge. St. Ignace Scuba runs charters on its boat Intrepid from the north shore, and two-tank trips leave Minogin Market Dock in Mackinaw City on the south side. The preserve keeps mooring buoys on most wrecks from late May to mid-September, so boats tie in rather than anchor on a hull. The Straits are an active shipping channel where a 274-metre freighter (900 feet) can pass close, so every ascent goes up the buoy line, and a rough lake can cancel a charter.

The preserve stretches over 383 km² (148 square miles), from Wilderness State Park to the Cheboygan area and across most of the South Channel. On the bottom lie a dozen or more buoyed wrecks, both intact and broken up: schooners, schooner-barges, brigs, wooden steamships and the steel Cedarville. The bridge splits the water between two lakes, with the Eber Ward in Lake Michigan and the William H. Barnum and St. Andrew in Lake Huron, so two wrecks in two lakes fit into one day. Early in the season several sites hold schools of spawning whitefish and perch, and near Mackinac Island divers visit formations of Mackinac breccia.

This suits wreck divers with cold-water experience, which the Mackinaw City charter asks for alongside Open Water certification. Water runs from about 4 °C (40 °F) to 20 °C (68 °F) in midsummer, and a drysuit is recommended. Several hulls sit below 30 m, and the Minneapolis, in the narrowest part of the Straits, runs a frequently strong current and is rated for advanced divers. All Great Lakes wrecks are protected and nothing may be removed.