For more than 12,000 years, people have traveled on the Great Lakes, from Native American dugout canoes to wooden sailing craft and steel freighters, and thousands of ships have made millions of voyages on these Inland Seas. The last 150 years have seen enormous growth in Great Lakes shipping, which remains critical to the national economy, but fire, ice, collisions, and storms have also claimed hundreds of vessels, including pioneer steamboats, wooden schooners, and steel freighters. Today, the 4,300 square-mile Thunder Bay National Marine Sanctuary protects 200 shipwrecks in the clear, fresh waters of Lake Huron, where they support diving, snorkeling, paddling, lighthouse visits, glass-bottom boat and kayak tours, and underwater exploration near Alpena.