The book will mainly target senior undergraduate and graduate students but also environmental managers will find it useful. The covered files is the theory and applications of GIS in marine sciences (mainly oceanography and fisheries), however related disciplines will be covered (e.g. Global Positioning System, Remote Sensing, Sonar Mapping, Statistical Modeling, Geostatistical Analysis etc). The textbook will serve as a comprehensive text with extensive additional material (a dedicated website with related data, specific GIS applications, statistical exercises and useful links.