In August 1914 Ernest Shackleton and his crew of twenty-seven sailors and scientists left Britain for the Antarctic on the Endurance, planning to cross the Antarctic on foot. Only 80 miles from Endurance's destination, the ship was caught in thick pack ice that eventually splintered and sank it. The men set up camp on ice floes that drifted on a frigid sea 2,000 fathoms deep. Eventually they managed to sail lifeboats to Elephant Island, one of the most uninhabitable islands on earth. Because the men were faced with sure death, Shackleton and a handful of his strongest men took the lifeboat James Caird 800 miles to South Georgia Island. The seventeen-day trip was unimaginably grueling. The men kept the boat afloat despite sixty-foot waves, thousands of them each day, and sub-zero temperatures navigating with only a sextant and an unreliable chronometer. When they reached their destination, they had to scale immense glaciers to get to help on the other side of the island. It took another three months to rescue the men who remained on Elephant Island. The entire ordeal lasted nearly two years.