|Builder:||Ramage and Ferguson, Ltd.|
|Launched:||20 September 1906|
|Christened:||As civilian yacht Agawa|
|Commissioned:||20 October 1917 as SP-575 and 31 December 1941 as PY-26|
|Decommissioned:||17 March 1919 and returned to civilian ownership until 1941|
|Struck:||24 June 1942|
|Fate:||Sunk 2 May 1942 by U-402|
|Beam:||27 ft 6 in|
|Draft:||12 ft 0 in|
|Speed:||12 knots (14 mph; 22 km/h)|
|Armament:||Three 3 inch gun mounts|
USS Cythera (SP-575/PY-26) was a US Navy patrol yacht, originally laid down as the civilian yacht Agawa for William L. Harkness, that saw service in the Atlantic during both World War I and World War II.
World War I
Originally constructed in Leith, Scotland and launched as the civilian yacht Agawa on 20 September 1906, she was subsequently leased from William L. Harkness by the US Navy in 1917 and commissioned as the USS Cythera (SP-575). Sailing from New York on 27 October 1917, Cythera arrived at Newport the next day and was assigned to Patrol Force, Atlantic Fleet. She cleared Newport 1 November with her squadron, and escorted and towed submarine chasers to European waters, before arriving at Gibraltar on 29 December. Based out of Gibraltar, she patrolled and escorted convoys between her base and Mediterranean ports in France, Italy, and Africa. She was decommissioned 17 March 1919, and returned to her owner two days later.
World War II
After serving under civilian operation for more than two decades, Cythera was reacquired from William L. Harkness widow Edith by the US Navy on 31 December 1941 and given the designation PY-26. Her conversion into a patrol vessel was completed 28 February, and she was placed in service 3 March 1942. On 2 May 1942, while escorting the Russian tanker Ashkhabad, she was torpedoed and sunk by the U-boat U-402 off the coast of North Carolina. Of the 71 crew on board at the time, only two survived and were picked up by the attacking submarine as prisoners of war.
- Blair 1996, p. 544.