For centuries, Antarctica—surrounded by thick sea ice and with winter temperatures dipping below -70 degrees Fahrenheit—was almost totally unexplored. Beginning in the late 19th century, however, fascination with the frozen landscape started to grow. Adventurers made repeated attempts to reach the continent—a period called the Heroic Age of Antarctic Exploration.
One such adventurer was Shackleton, who had served in Britain’s Royal Navy. By 1910, he had already taken part in two Antarctic expeditions and had trekked within about 100 miles of the South Pole, Earth’s southernmost point. For his third effort, on the Endurance, Shackleton spent nearly two years raising money and recruiting crew members. He knew the mission would be hazardous, with long hours of darkness in the bitter cold and no promise of a safe return.
Shackleton and his crew set out from London, England, on August 1, 1914. As the Endurance approached Antarctica, the journey became increasingly difficult. For weeks, the crew slowly wove the ship through cracks in the frozen Weddell Sea. Then, on January 18, 1915, the Endurance could move no more. The ship was, as one crew member later put it, “frozen, like an almond in the middle of a chocolate bar.”