Research of the origins of life in connection with a marine environment started at the end of the seventies, when the `black smokers' in the Pacific were discovered and the Red Sea deep hydrothermal brines were found to be a fruitful environment for abiotic synthesis of life precursors. For a while this research was categorised under the heading `chemistry', but in less than a decade the topic became fully integrated into the science of 'oceanography'. The Scientific Committee on Oceanographic Research (SCOR) initiated Working Group 91: Chemical Evolution and Origin of Life in Marine Hydrothermal Systems'. This volume contains the final report of this working group.