History of submarines few years before the US, and paralleled subsequent US development in this area. In the 1950s, nuclear power partially replaced diesel-electric propulsion. The sailing of the first nuclear-powered submarine, the USN ""Nautilus"" in 1955 was soon followed by similar British, French and Russian boats. Equipment was also developed to extract oxygen from sea water. These two innovations, together with inertial navigation systems, gave submarines the ability to remain submerged for weeks or months, and enabled previously impossible voyages such as the crossing of the North Pole beneath the Arctic ice cap by the USS "Nautilus" in 1958. Most of the
North Pole heat), rather than at altitude on a continental land mass. Despite being an ice cap, it shares some characteristics with a tundra climate ("ETf") due to the July and August temperatures peaking just above freezing. Winter temperatures at the northernmost weather station in Greenland can range from about , averaging around , with the North Pole being slightly colder. However, a freak storm caused the temperature to reach for a time at a World Meteorological Organization buoy, located at 87.45°N, on December 30, 2015. It was estimated that the temperature at the North Pole was between during the storm. Summer