North Pole-1 was established on 21 May 1937 and officially opened on 6 June, some 20 kilometres (12 mi) from the North Pole by the expedition into the high latitudes Sever-1, led by Otto Schmidt. The expedition had been airlifted by aviation units under the command of Mark Shevelev. "NP-1" operated for 9 months, during which the ice floe travelled 2,850 kilometres (1,770 mi). The commander of the station was Ivan Papanin. On 19 February 1938 the Soviet ice breakers Taimyr and Murman took four polar explorers off the station close to the eastern coast of Greenland. They arrived in Leningrad on 15 March on board the icebreaker Yermak.