Ernest Shackleton's Trans-Antarctica expedition of 1914 - 1917 is one of the most incredible adventure stories of all time. It is remarkable even for an era and region that already has far more than its fair share of incredible tales of heroism and fortitude in the face of appalling hardships.
The intention was to cross the Antarctic continent from one coast to the other via the South Pole. In the event, the expedition never set foot on continental Antarctica. The expedition managed to survive the loss of their ship in the middle of the Antarctic pack ice at a time when there was no chance of contacting the outside world, let alone of being rescued.