First to cross the Antarctic Circle (Jan 17, 1773) on Resolution during 2nd voyage. Circumnavigated Antarctica (never sighted land) – proved no habitable southern continent existed. "I circumnavigated the globe at high southern latitude... and put an end to the speculation."
Russian Imperial Navy. First to sight Antarctic mainland (Jan 27, 1820) – Princess Martha Coast (Fimbul Ice Shelf). Commanded Vostok & Mirny. Mapped large coastline segments. Often credited with first landing (disputed).
US Exploring Expedition ("Ex. Ex."). 6 ships, 346 men. Charted 1,500+ miles of coastline (Wilkes Land), proved continental scale. Collected 60,000+ specimens (Smithsonian foundation). Controversial leadership, but scientific legacy immense.
These three laid the cartographic and scientific groundwork for the Heroic Age.