Mariner, a 234 gross ton steam tug, was built in 1906 at Camden, New Jersey. She was employed by the Panama Canal Commission during the construction of the Panama Canal and after its completion. Taken over by the U.S. Navy in early 1918, she was commissioned as USS Mariner (with no identification number) in February and served in the Panama Canal Zone area on patrol and tug duties through the rest of World War I. Mariner was returned to owners in January 1919 and resumed her civilian work.