Antarctica: Operation Deep Freeze 1956-60: 1956 (Dec. 15) Operation Deepfreeze I Hydrographic Party envelope with Task Force 43 and U.S.C.G.C. Eastwind penguin cachet cachet and enclosed letter, 1958 (Jan. 1) cover with U.S. Naval Mobile Special Construction Battalion, Hallett Station and I.G.Y. cachets, also 1964 (Feb. 23) postcard sent from Ross Dependency by Third Officer, U.S.N.S. “Chattahoochee” with cachets. (3 items) (Image1)