USS Euphemia (SP-539) was a United States Navy patrol vessel in commission from 1917 to 1919. Euphemia was built in 1898 as a private motorboat. In 1917, the U.S. Navy purchased her for use as a section patrol vessel during World War I. She was commissioned as USS Euphemia (SP-539) on 25 June 1917. Assigned to the 1st Naval District, Euphemia operated on patrol duties in northern New England waters for the rest of World War I and into 1919. Euphemia was stricken from the Navy List on 21 October 1919 and sold in 1920.