(Grand Drillling Somerson) This field off the south shore of Grand Lake St. Marys, Mercer County, Ohio may have been one of the first offshore oil fields. Wells interconnected by boardwalks. Circa 1890. Note: In several AAPG publications (Oil on their shoes, by Ellen Sue Blakey and AAPG Explorer Special Issue: A century) photo was donated by James A. Noel and indicated photo taken about 1915. An image of off-shore oil drilling at Grand Lake St. Marys in the 1890s. Source is Ohio Department of Natural Resources, Division of Geological Survey.