The first voyage under the North Pole was made from August 1 to August 5, 1958, by the United States submarine Nautilus. She crossed from Point Barrow, Alaska to the Greenland Sea, traveling 1,830 miles under the Polar ice cap and passing the geographic North Pole on August 3.
The Nautilus could maintain submerged speeds of over 20 knots almost indefinitely.
She was designed to run on direct water heat from an atomic pile. The crew were shielded so well from the pile that in a year's cruise they received less radiation than that set by the American Bureau of Standards as permissible for a single week.
Nuclear submarines are equipped with alternative electrical power for use should the reactor fail.