Thanks to our friends at Wikipedia:
Bounded by four of the five Great Lakes, plus Lake Saint Clair, Michigan has the longest freshwater shoreline in the World, and the second longest total shoreline in the United States next to Alaska (excluding island shorelines),[4] and in 2005 had more registered recreational boats than any state except California and Florida.[5] A person in Michigan is never more than 85 miles (137 km) from open Great Lakes water and is never more than 6 miles (10 km) from a natural water source.
