USS Lydonia (SP-700) was United States Navy patrol vessel in commission from 1917 to 1919 that saw service during World War I. Prior to her U.S. Navy service, she had been William A. Lydon's private yacht, Lydonia II, from 1912 to 1917. She spent most of the war based at Gibraltar, escorting and protecting Allied ships in the Mediterranean and along the Atlantic Ocean coast of Europe. After her U.S. Navy service ended, she served from 1919 to 1947 in the United States Coast and Geodetic Survey as the coastal survey ship USCGS Lydonia (CS-302).