Book excerpt: Critical human activities take place at sea, including trade, tourism, migration, scientific exploration and resource exploitation. This book offers a novel and important contribution to an ever-emerging cross-disciplinary subject matter and challenges human geography's preoccupation with the terrestrial. Linking to new theoretical debates shaping the geographic discipline, (such as affect, assemblage, emotion, hybridity and the more-than-human) this volume unlocks new knowledge concerning the human geographies of ocean space and dispenses with fixed conceptions of space. It advances geographical understanding based on the world as 'becoming', changing, mobile and processional.