The dataset comprises hydrographic data, including salinity, temperature, depth, dissolved oxygen, transmittance (for suspended sediment), chlorophyll, irradiance, and current velocities. Both oceanographic and benthic measurements of nutrients (nitrate, nitrite, silicate, phosphate and ammonium), phytoplankton and zooplankton abundance, dissolved and particulate trace metals, primary and bacterial production, sulphur compounds and halocarbons were collected, as well as atmospheric physical and chemical measurements. The data were collected in the North Sea between August 1988 and October 1990 over a series of 38 cruises on RRS Challenger. Oceanographic measurements were taken using hydrographic profilers, moored instruments and shipboard underway systems. Underway meteorological data were also collected in addition to a comprehensive atmospheric sampling programme. Both continuous and discrete water samples were collected, providing biogeochemical and biological data. These were supplemented by net hauls. Benthic processes were investigated with sediment cores taken on eight survey cruises at six sites of varied character, three being in the area of summer stratification. Water and benthic sample analyses were supplemented by results of seabed and shipboard incubation experiments. The North Sea Project evolved from a NERC review of shelf seas research, which identified the need for a concerted multidisciplinary study of circulation, transport and production. The Proudman Oceanographic Laboratory (POL), now the National Oceanography Centre (NOC) hosted the project. It involved over 200 scientists and support staff from the Natural Environment Research Council (NERC), the Ministry of Agriculture, Fisheries and Food (MAFF - now DEFRA) and other academic institutes. The data are held at the British Oceanographic Data Centre and are available on CD-ROM.