On December 10, 1964, "Edisto" departed for the Antarctic as a unit of the task force for Operation Deep Freeze 65 on an assignment unprecedented in icebreaker history. She had the responsibility for constructing the new Palmer Station for marine biological studies on Anvers Island off the Antarctic Peninsula. No sooner had she accomplished this assignment and returned to Boston, than "Edisto" was ordered to sail on a polar rescue mission. Drifting south was the Ice Island Arlis II, with 20 scientists on board waiting to be evacuated before the island broke up underneath them. Departing Boston on April 6, 1965, after a stay of only five days, she battled some of the thickest and hardest ice ever encountered by an American icebreaker to moor alongside Ice Island Arlis II and to effect the evacuation of the men and equipment.