This document was originally approved by GESAMP (the IMO/FAO/UNESCO/WMO/WHO/IAEA/UN/UNEP Joint Group of Experts on the Scientific Aspects of Marine Pollution) in March 1983 at its thirteenth session for publication as GESAMP Reports and Studies No. 19. Recognizing that its usefulness is far broader than its application to calculations of concentrations of radioactive materials in the deep sea, the IAEA has undertaken to republish the report in its Technical Reports Series with the concurrence of the other technical bodies of GESAMP. Contents: Introduction; General requirements for ocean models for contaminant transport; Oceanographic processes relevant to deep-sea contaminant transport; Survey of existing and potential models; Recommended models; Future research needs; Appendix I: Geochemical properties and observations of the deep ocean; Appendix II: Natural history of the ocean; Appendix III: Quantitative estimates of various biological processes; Appendix IV: A simple finite ocean diffusive model; Appendix V: Parametrization of boundary scavenging processes; Appendix VI: Vertical, one-dimensional, one- and two-layer boundary scavenging models; Appendix VII: The effects of strong local scavenging; Appendix VIII. A two-dimensional ocean dispersion model; Appendix IX. A hybrid vertical scavenging model; Appendix X. Estimation of concentra-tions in food chains; References; Glossary; List of basic symbols used.