An ice pier is a man-made structure used to assist the unloading of ships in Antarctica. It is constructed by pumping seawater into a contained area and allowing the water to freeze. By repeating this procedure several times, additional layers are built up. The final structure is many metres in thickness, and strong enough to support container trucks. Operation Deep Freeze personnel constructed the first floating ice pier at Antarctica’s southernmost sea port at McMurdo Station in 1973. Ice piers have been in use each summer season since, at McMurdo’s natural harbor at Winter Quarters Bay located at (77°50′S166°40′E).