How do fishers extend their bodies and senses to work beneath the surface of the sea in places they cannot see, have never been, and could not survive in? And at what risk? This book explores how fishers make the sea productive through their labour, using technologies ranging from wooden boats to digital GPS plotters to extend their senses and range of effective work, in the process creating familiar places in a seemingly hostile environment. It shows how the lives of fishers are deeply affected by capitalist commodity relations. Drawing on years of participant observation at sea in the west of Scotland, the author worked on a Nephrops prawn trawler, lived on a boat in harbours and voyaged along the coast. The book makes a unique contribution to understanding human-environment relations, examining the places fishers create and name at sea, as well as fishers’ technologies and navigation practices. Combining anthropology, phenomenology and political economy, the ethnography offers new approaches for analyses of human-environment relations and technologies in a Marxist framework. It also contributes to the social studies of fisheries through an analysis of how deeply fishing practices and social relations are shaped by political economy.