The Northern Seas Programme dataset comprises hydrographic, biogeochemical, biological and meteorological data. Hydrographic profiles provided measurements of parameters such as temperature, salinity, fluorescence and dissolved oxygen, while current velocities and acoustic backscatter were also measured. A comprehensive water sampling program permitted the collection of biogeochemical data including concentrations of various organic compounds, dissolved gas concentrations and radioactivity. Water samples were also analysed for phytoplankton, zooplankton and viruses. Larger biological samples were obtained from the water column using trawl nets and cetacean distributions were monitored using hydrophone arrays. Sediment samples were collected at various locations and analysed for biogeochemical parameters and zoobenthos. Sample data were supplemented by those derived from experiments, while bathymetry and meteorological parameters were measured across the study area. Data collection was undertaken in the Irish and northern North Seas, across the NE Atlantic and up to the marginal Arctic pack ice zone. This includes the territorial waters of the UK, Norway and the Russian Arctic, and extends from coastal fjords to the ocean margins. The data were collected during the period 2001-2007 over a number of cruises: RRS Discovery cruise D257, RRS James Clark Ross cruises JR75 and JR127, RRS Charles Darwin cruise CD176 and FS Poseidon cruise PO300/2. Measurements were taken using a variety of instrumentation, including conductivity-temperature-depth (CTD) profilers with attached auxiliary sensors, bathymetric echosounders, sediment samplers, trawl nets and acoustic Doppler current profilers (ADCPs), while incubation chambers were used for shipboard experiments. The programme was designed to advance the understanding of how marine systems in Northern Seas respond to environmental and anthropogenic change and was developed in three themes: Theme A - Understanding fjordic systems insights for coastal and oceanic processes; Theme B - Ocean Margins: the interface between the coastal zone and oceanic realm; Theme C - Measuring and modelling change: sea sensors and bioinformatics. Theme B included the Ellett Line Time Series. The Northern Seas Programme was co-ordinated by the Scottish Association for Marine Science (SAMS). Data from the programme are held at the British Oceanographic Data Centre.