USS Surf (SP-518) was a steam yacht that was offered to the United States Navy in 1917 but was never accepted.

Surf was built as a civilian steam yacht in 1898 by Ramage & Ferguson at Leith Scotland, for E. D. Lambert of Berkshire, England.

[2] Dr. Harriss loaned the Surf to the Navy and the American Red Cross for use as an Ambulance ship in May 1917, he assumed all the costs for painting her in Red Cross livery, her maintenance and the salaries of the doctors and nurses detailed to her, as well as offering his own services.

[5] From 30 July 1918 she started taking 120 Army patients a time from the United States General Hospital No.

1 on day trips, three times a week, along the Hudson River as a recreation boat, musical entertainment being provided.