It is, USS Castle Rock.
USS Castle Rock, a 1,766-ton Barnegat class small seaplane tender, was built at Houghton, Washington, and was commissioned in October 1944. She left San Diego for the Central Pacific in December 1944 and, upon arrival at Eniwetok in January, began escorting convoys between Saipan, Guam, and Ulithi. In March she became tender for seaplanes at Saipan, while also serving as a local escort.
Above from the Naval Historical Sight.
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