The U.S. Coast Guard Cutter Mackinaw is the nation's only heavy icebreaking vessel assigned exclusively to the Great Lakes. The Mackinaw, seen here during its launch in April 2005, boasts a state-of-the-art navigation system and Finnish-built Azipod propulsion system. The Azipods generate 9,119 shaft horsepower, which aids the Mackinaw as it crashes through ice sheets up to 10 feet thick. The vessel reaches a maximum speed of 15 knots (17 mph) and stretches 240 feet from bow to stern. The Great Lakes, which connect to the ocean via the St. Lawrence Seaway, are vital shipping lanes year-round. Without an icebreaker to clear a path for ships, the region's economy would lose hundreds of millions of dollars annually.

Click to see U.S. Coast Guard Cutter Mackinaw.

Chad Vander Veen  |  Associate Editor