When radionuclides are discharged into coastal waters, man is exposed via several pathways, including seaspray and seafood. In predicting the magnitude of the transfer and the radiological consequence in the short- and long-term, some understanding of the processes controlling radionuclide levels in the adjacent near-shore waters is necessary. A recent study of Pu and Am concentrations in the coastal waters near the Sellafield nuclear reprocessing plant in Cumbria has been carried out, primarily to improve the source-term of a sea-to-land seaspray model. The data are, however, applicable to other pathways, particularly the ingestion of actinides in seafood. The results suggest that the actinides remain in these near-shore waters and are available for sea-to-land transfer for more than six years following their discharge from Sellafield. During this time, variations in suspended particulate loadings appear to be the most important influence on their seawater concentration. © 1990.