The data set comprises hydrographic and biogeochemical and biological measurements including temperature, salinity, currents, chlorophyll, dissolved organic and inorganic carbon and nitrogen, suspended matter concentrations, nutrients, plankton and fish. The results of primary production experiments are also included. The data were collected from the Bristol Channel, Severn Estuary, Celtic Sea and Plymouth Sound between 1971 and 1983. Measurements were taken over a series of more than 100 cruises, many with more than 50 stations. The most intensive sampling took place before 1975. The original data were collated and stored at Institute for Marine Environmental Research (IMER), which became Plymouth Marine Laboratory in 1988. As this is a large and important data set, which was previously held in an inaccessible format, it was selected for long-term archival at BODC as part of the NERC SEEDCORN programme. The data have been extracted, loaded into a relational database and are available on CD-ROM.