The physical, geochemical and biological processes that lead to the dispersion of radionuclides throughout the marine environment and to interactions with man and his food chain are outlined. Although much remains to be understood about the details of these processes, certain limits may be put on radionuclide transport rates. Some of these limits are applicable to many situations, others are strongly dependent on the half-life, reactivity, etc., of the radionuclide or on the details of its source. Although physical and geochemical processes tend to dominate transfer mechanisms, the biological aspects of radionuclide transport attract much attention. It is shown that, even though our knowledge of deep-sea biology is far from perfect, certain quantifiable limits can also be put on these transport rates. An attempt is made to put these and other oceanic aspects of the deep-sea disposal of radionuclides into perspective.