‘Seabed fluid flow’ encompasses a wide range of fluids (gases and liquids) that pass from sediments to seawater, involving natural processes that modern science would pigeon-hole into a wide range of disciplines, mainly in the geosciences, biosciences, chemical sciences, environmental sciences, and ocean sciences; they also impinge on (or are affected by) human activities. With our background, it is inevitable that the most prominent fluid in this book is methane. There is a vast literature on hydrothermal vents, and a growing interest in submarine groundwater discharge with which we do not wish to compete. However, we recognise the importance of considering all forms of seabed fluid flow so that similarities and differences in the processes may be considered. We have attempted to assimilate all forms, manifestations, and consequences of seabed fluid flow of whatever origin.

It is impossible, in a single volume, to do justice to such a multidisciplinary subject. The pace of research has progressively increased since our own interests in pockmarks and seeps began. Of particular significance is the move of the petroleum industry from the continental shelves into the deeper waters of the continental slope and rise; this has rejuvenated research in deep-seabed processes, and has resulted in rethinking many old ideas not least because of the discovery of many deep-water features associated with seabed fluid flow.