USS Tamarack (SP-561) was a United States Navy patrol vessel in commission from 1917 to 1919. Tamarack was built as a private motor yacht of the same name by Nevins Shipyard at City Island in the Bronx, New York, in 1915 to a design by the firm of Swasey, Raymond, and Page. On 25 June 1917, the U.S. Navy acquired her under a free lease from her owner, Leonard Breed of Flushing, New York, for use as a section patrol craft during World War I. She was commissioned as USS Tamarack (SP-561) on 18 September 1917.