Historians credit Grand Lake St. Marys in Ohio with the first submerged oil wells around 1891, drilled from platforms on piles into fresh water, five years before the Summerland field in Santa Barbara County, California drilled the first submerged wells in salt water in 1896. Whether ocean engineering should date the first true offshore well to the earlier freshwater lake wells or reserve the title for the first saltwater, open-ocean wells is a definitional choice historians have not settled.
What would resolve this A documented contemporary industry or engineering definition of offshore drilling from the 1890s that explicitly includes or excludes freshwater lake wells would settle whether Grand Lake St. Marys or Summerland holds true priority.
OpenHistory of petroleum and ocean engineeringOffshore Drilling (Wikipedia)