When Google Earth 5.0 was released back in February, it included the capability to view the world ocean landscape from beneath the water surface. This capability now extends to the “Third Coast” of the United States, the Great Lakes. Through a cooperative effort with the NOAA Great Lakes Environmental Research Laboratory (GLERL) and the NOAA National Geophysical Data Center, Google Earth now incorporates detailed bathymetry for the five Great Lakes. Users will be able to explore features such as the canyons and shoals in eastern Lake Superior, the Lake Michigan mid-lake reef complex, and the old river channel, now underwater, that once connected Lakes Michigan and Huron at the Straits of Mackinac.

The Great Lakes are the largest system of fresh surface water on earth, containing roughly 18 percent of the world supply. The lakes contain enough water to cover the entire surface of the continental United States to a depth of 9 feet. The Great Lakes span more than 750 miles from west to east and their shoreline is equal to almost 44 percent of the circumference of the earth. Michigan's Great Lakes coastline alone is over 3,200 miles long, which is more coastline than any state but Alaska.

To highlight some of the interesting coastal and subsurface features of the Great Lakes, the NOAA Great Lakes Environmental Research Laboratory has assembled a narrated Google Earth tour, which you can download here. You can also watch the tour, using the Earth API, below: