USS St. Mary's or USS St. Marys has been the name of more than one United States Navy ship, and may refer to:

See also

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  • St. Mary's, was a side-wheeled steamer acquired by the U.S. Navy and renamed USS Hatteras in 1861
  • CSS St. Mary, a Confederate States Navy ship captured in 1863 by Union forces and commissioned into the U.S. Navy as USS Alexandria
  • USS St. Mary's River