The mapping described in this paper was done to provide the necessary information for the hydrological research in the Lappträsket representative basin. This IHD-basin (approximately 1000 km2) is situated right on the Artic Circle with its main run-off station at lat. 66˚10’ N and
long. 21°50’ E. The basic work was done by aerial photo interpretation on a scale of 1:30 000 followed by same field work along the lines. During the field work the photo interpretation could be checked and certain features added. All the collected information was finally transferred from the photographs to a photomap at 1:20 000 with contour lines.