Shackleton's first voyage was with Captain Robert Falcon Scott and Edward Wilson (on the British National Antarctic Discovery Expedition 1901-1904), in which they undertook a sledge journey over the Ross Ice Shelf to a latitude of 82° 16' 33 S (the South Pole is at 90°).

In 1907-1909, Shackleton led the British Antarctic (Nimrod) Expedition. Shackleton's sledge expedition went within 97 miles (156 km) of the South Pole (T.W. Edgeworth David led another sledge expedition that reached the area of the South Magnetic Pole). During this expedition, the Victoria Land Plateau was claimed for Britain. Shackleton was knighted upon his return.

Shackleton led the British Imperial Trans-Antarctic Expedition (1914-16), which planned to cross Antarctica from the Weddell Sea to McMurdo Sound (2,000 mi = 3,200 km), but instead drifted at sea for 10 months - and then their ship Endurance was crushed by pack ice in 1915. The crew escaped to Elephant Island (in the South Shetland Islands); Shackleton and a few others went over 800 miles for help in a life boat, and eventually rescued the others.

On his last expedition, to Enderby Land (in Antarctica), Shackleton died aboard ship and was buried on South Georgia Island. Shackleton wrote accounts of his journeys in "The Heart of the Antarctic" (1909) and "South" (1919).

Sir Raymond Priestley (1886 - 1974), a British Geologist and Antarctic explorer who accompanied Shackleton on the 1907-1913 Antarctic expeditions, said, "For scientific leadership, give me Scott; for swift and efficient travel, Amundsen; but when you are in a hopeless situation, when there seems to be no way out, get on your knees and pray for Shackleton."