Wisconsin has an unusual new “museum.” If you want to visit, you’ll have to put on your diving gear first.The Wisconsin Shipwreck Coast National Marine Sanctuary contains dozens of shipwrecks at the bottom of Lake Michigan. The U.S. government designated the 962-square-mile area as a marine sanctuary last year. The designation sets up protections to preserve the artifacts, but visitors can still snorkel and dive to the wrecks to explore them. In addition to 36 known shipwrecks, experts believe there may be nearly 60 others in the protected area. The discovered wrecks date as far back as the mid-1800s, when great numbers of people were moving west across America in search of more land. The Great Lakes, including Lake Michigan, played a key role in the migration, with ships ferrying both people and supplies to new settlements. Today, many of the ships are still in excellent condition, preserved by the cold fresh water. They’re valuable time capsules, says Russ Green, a scientist at the National Oceanic and Atmospheric Administration. He adds: “These historic shipwrecks tell America’s story.”