The first person to reach the North Pole was an engineer in the American Navy named Robert Edwin Peary, who reached the Pole on 6 April 1909, along with his employee Matthew Henson and four Inuit men named Seeglo, Ootah, Ooqueah, and Egigingwah. Although his achievement was shadowed with doubt for almost a century, a 2005 expedition by a British explorer named Tom Avery and four others were able to recreate Peary's journey with replica wooden sleds pulled by Canadian Eskimo Dog teams, taking 36 days and 22 hours to reach the North Pole, a figure only 5 hours faster than that given by Peary.
The Earth's North Pole is extremely isolated and cold. As there is little reason to travel there except to make a point, the total number of explorers who travel there numbers no more than a couple hundred per year. Fly-bys have been made by plane and airship, and US and Soviet submarines have passed by the North Pole and even surfaced there. Lacking solid ground, the North Pole is covered by constantly reshuffling thick sea ice. This makes it impossible to build any permanent structure there.
During the summer, the North Pole receives 24 hours of sunlight, and during the winter, 24 hours of darkness. To understand why, recall that the Earth's axis is not directly perpendicular to the plane of the ecliptic, but rather is offset by a factor of 23 degrees, called the axial tilt. So while the majority of the planet is thrust in and out of sunlight every 24 hours, small portions around the North and South Pole experience 6-month nights and days. Of course, this makes them all the more hostile to would-be polar colonizers or scientific researchers.
Numerous controversies surrounded the first polar expedition. Except for Peary, no one on the trip was trained in navigation, and thus no one could confirm Peary's navigational work. In a book later published by Henson, he recalled the trip as difficult, involving torturous detours to avoid ice ridges and areas where the ice pack grew thin. This contradicted Peary's account of a fast and direct trek to the Pole. However, as stated before, their trip was recreated by explorers using period equipment, and thus looks more plausible than many historians of the 20th century would have thought.