The marine forecast is perfect. Winds are southwest at 5 knots and waves are 1 foot or less. The surface of Lake Erie is almost placid, beckoning a local diver to don his gear and dive 200 feet to the lake floor below. He begins his descent through tepid water, but as he passes through the thermocline the water temperature drops 30 degrees, cold water envelops his body and visibility is limited. Suddenly, out of the darkness the mast of a ship comes into view, beckoning from its watery grave. The diver's doubt is replaced by exhilaration as the wreckage of a ship from the 1800s is unveiled, perfectly preserved in all her glory.