In August 1979 a seismic-refraction survey was carried out along a 1900 km long line through Scandinavia in order to investigate the structure of the lithosphere and asthenosphere beneath the Baltic Shield. Large explosions at the shotpoints near Karlskrona in the south (B) and near the North Cape in the north (H and I), were recorded along the whole line which served to penetrate the earth's mantle to depths of approximately 400 km. In order to be able to control the data for lateral inhomogeneities in the lower lithosphere and in the crust, a series of intermediate shotpoints was arranged with an average spacing of about 300 km. Recording stations were positioned at about 3 km interval for distances up to 1000 km and 10 km interval for the large shots being recorded at distances beyond 1000 km. Along the main line through Scandinavia 96 recording stations of type MARS 66 were used and 28 explosions ranging in size between 1.8 and 8 tons TNT were fired at 8 shotpoints.