Abstract In the introduction the limits, size, and bottom configuration of the North Sea are discussed briefly. Also a short account of the tidal movements, the tidal currents, and the relations of the salt content is given. In the main part of the paper a picture of the present-day distribution of North Sea sediments is sketched. The deposits consist mainly of sand and sandy silt. Sediments of this type amount to about 60 per cent of the total deposits; coarse sand and clay are represented by about 20 per cent each. An interpretation of sediment charts based on qualitative indications of bottom deposits in hydrographic charts runs into difficulties owing to lack of current measurements. An attempt is made to draw conclusions from geologic history as to the source and the present distribution of the sediments of the North Sea Basin and as to the nature of the coasts and the depth configuration of the sea bottom. The results of investigations make it probable that the present distribution of sediments in the North Sea Basin in its major features has been determined by sedimentation during the Quaternary glacial periods. In the southern part of the North Sea, and especially in areas near shore, hydrodynamic forces have led to considerable changes in the sediments in the past. Furthermore, as indicated by the close relationship between the nearshore sediments and the shoreline, these forces are still modifying the deposits. The large-scale modifications that are taking place in this way are illustrated by a few examples. The paper is closed with a short account of several problems that remain to be solved and of the desirability of cooperation between various research institutes in the solution of these problems.