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
Penny Ice Cap Penny Ice Cap The Penny Ice Cap is a ice cap in Auyuittuq National Park of Baffin Island, Nunavut, Canada. It forms a high barrier on the Cumberland Peninsula, an area of deep fiords and glaciated valleys. It is a remnant of the last ice age. During the mid-1990s, Canadian researchers studied the glacier's patterns of freezing and thawing over centuries by drilling ice core samples. The ice cap has been thinning and its valley glaciers have been retreating in recent decades related to rising summer and winter air temperatures across the eastern Arctic. The ice cap is named after