"Whiteside" remained at San Francisco until the summer of 1946. On 5 June, she got underway for the Marshall Islands to provide support services for "Operation Crossroads", the large-scale nuclear tests conducted at Bikini Atoll that summer. She reached Kwajalein Atoll on 17 June and remained in the Marshalls assisting the operation until the end of August when she embarked upon a voyage that took her to Okinawa, Guam, Eniwetok, and thence back to Pearl Harbor. The ship remained at Pearl Harbor from the end of October to the latter part of November.