Full grain size distributions were compiled from over 30,000 sediment samples collected by national and European surveys conducted during the past 50 years. The percentage mud content was calculated from the cumulative distribution curves as the proportion of the grain size fraction smaller than 63 µm using nonlinear logistic regression. Multivariate geostatistics (external drift kriging) was employed to spatially predict the mud content using information on water depth as a trend variable. Data Provider: Research and Technology Centre, West Coast, Büsum, DE Federal Maritime and Hydrographic Agency, Hamburg, DE Senckenberg Marine Research, Wilhelmshaven, DE Helmholtz-Zentrum Geesthacht, Geesthacht, DE BioConsult SH GmbH & Co. KG, Husum, DE British Geological Survey, Edinburgh, UK Marine Scotland - Marine Laboratory, Aberdeen, UK Institute of Geology, Hamburg University, Hamburg, DE Royal Netherlands Institute for Sea Research, Texel, NL Geological Survey of the Netherlands, Utrecht, NL School of Ocean Sciences, Bangor University, Bangor, UK Centre for Environment, Fisheries and Aquaculture Science, Lowestoft, UK Geological Survey of Norway, Trondheim, NO Geological Survey of Denmark and Greenland, Copenhagen, DK Geological Survey of France, Orléans, FR Det Norske Veritas, Hørvik, NO Hamburg Port Authority, Hamburg, DE Project “Management, Research and Budgeting of Aggregates in Shelf Seas related to End-users” (2002-2006), Ghent University, BE Project “North Sea Benthos Survey 1986”, International Council for the Exploration of the Sea (ICES), Copenhagen, DK Project “North Sea Benthos Project 2000”, International Council for the Exploration of the Sea (ICES), Copenhagen, DK Project “Geopotential Deutsche Nordsee” (2009-2013), http://www.gpdn.de/ Management Unit of the North Sea Mathematical Models, Royal Belgian Institute of Natural Sciences, Brussels, BE International Council for the Exploration of the Sea, Copenhagen, DK Publishing Network for Geoscientific & Environmental Data, Alfred Wegener Institute, Bremerhaven, DE Deltares, Utrecht, NL