The triple disaster of the 11 March 2011 earthquake, tsunami and subsequent radiation releases at Fukushima Dai-ichi are unprecedented events for the oceans. This special issue (SI) seeks to bring together manuscripts focused on the impacts and fate of Fukushima Dai-ichi nuclear power plant radionuclides that were released to the ocean. This includes studies of the relative path and magnitude of the radioactive releases, range of radionuclides released, dose assessments, levels of contaminants in the sea water, sediment and biota, dispersion patterns measured and predicted for both near and far fields. Related studies of atmospheric transport pathways and deposition on land, as they relate to ocean studies, are also appropriate for this SI. Studies of the transport of radionuclides to the ocean via rivers, run-off and groundwater are also appropriate. Manuscripts can include both field and modeling results, as well as new radionuclide analytical methods used to understand the impacts of Fukushima radionuclides on the oceans.