Abstract The basic features of the Arctic are caused in part by the geomagnetic relationships, in part by the inclination of the axis of the earth in relation to its orbit, as well as by the physio-graphic and topographic conditions. To start from the very top: the geomagnetic condition allows interaction between solar plasma and the upper atmosphere, causing magnetic storms and aurora which disturb magnetic measurements and the propagation of the radio waves. This gives navigation and communication difficulties. However, it also makes the Arctic a most important scientific window to the outer space. The geography of the Arctic can be described as a centrally located ocean, surrounded by low land and a few high mountain ranges and narrow straits leading to the world oceans. In this way it differs fundamentally from the Antarctic, which is a continent surrounded by a big ocean. The Arctic climate, although polar, is less severe than the Antarctic one. The features of the Arctic, which give most problems to the activities of man, are of two types: the permanent pack ice filling up the Arctic Basin and expanding into adjacent seas during winter, the permafrost and particularly the thawing during the summer of the 1–2 m thick uppermost layers of the soil. In addition to the description of the geophysical characteristics of the various Arctic regions or zones mention is made of biologic features, the indigenous people and of environmental matters.