Extending critical geopolitical analysis to investigate an unlikely venue, Rachel Squire brilliantly shows how American cold war geopolitical culture was a combination of science, masculinity and exploration. This fascinating account of a nearly forgotten scientific project explores the underwater world of Sealab, its aquanauts, scientists and their dangerous experimental habitat, built in the quest to dominate the frontier space of the ocean. -- Simon Dalby, Balsillie School of International Affairs, Wilfrid Laurier University A fascinating study of a little-known story in the Cold War. Using archival and other historical sources, Squire takes us beneath the surface to explore the world of Sealab with its multiple geographies. Engagingly written and conceptually innovative, this is an important contribution to political geography and wider debates about territory, volume and materiality. -- Stuart Elden, Professor of Political Theory and Geography, University of Warwick.