One of the greatest men in Norway's history, Nansen is best remembered for his explorations of the Arctic, although he made many contributions to science, humanitarianism, and politics. Born at Store-Froen in Norway, he graduated in zoology from the University of Christiania, now Oslo. Nansen was appointed curator of the Bergen Natural History Museum in 1882, later becoming successively professor of zoology (1896) and professor of oceanography (1908) at the Royal Frederick University, Christiania. He helped found the International Commission for the Study of the Sea and was director of its Central Laboratory from 1901.

In 1888–89, after several preliminary expeditions, Nansen was the first to explore and describe the uncharted Greenland icecap, trekking from east to west and proving that the island is uniformly covered with an ice sheet. While wintering at Godthaab, Nansen spent some time studying the Eskimos, later publishing his observations as Eskimoliv (1891; Eskimo Life). Using a specially constructed ship, Fram (Forward), designed to withstand ice-pressure, Nansen then (1893–96) proceeded on his epic expedition to the North Pole. Allowing his ship to freeze in the ice, it drifted northwards (thus proving the existence of a warmer current from Siberia to Spitzbergen). Nansen left the ship and continued northward by sled to 86°14′N – only 200 miles (320 km) from the North Pole and further north than anyone had ever been before. Nansen described his Arctic journey in Farthest North (2 vols. 1897). He made further oceanographic expeditions to the northeast Atlantic, Spitzbergen, the Barents and Kara Seas, and to the Azores. In addition to explaining the nature of wind-driven sea currents and the formation of deep- and bottom-water, Nansen did much valuable work in improving and designing oceanographic instruments. In a quite different field his paper on the histology of the central nervous system is considered a classic.

In later life Nansen became a dedicated humanitarian. He assisted in famine relief and aid for refugees after World War I, for which he received the Nobel Peace Prize in 1922. As a politician, he influenced the separation of Norway from Sweden (1905), was a member of the Disarmament Committee (1927), and was Norway's first ambassador to Britain (1906–08).