In an era of increasing geopolitical tensions, disruptive technologies, and the rise of authoritarianism, the question of who masters the seas is more than ever central to the future of the international order. But while naval operations, maritime security, and ocean governance have become increasingly relevant in world politics, the concept and definition of seapower have largely been neglected by the scholarship in the international relations field. Seapower in the Post-modern World fills this gap with an analysis of the naval, economic, and ideational dimensions of seapower from antiquity to today. Exploring the extent to which the permanent elements associated with seapower – such as technology, commerce, and maritime culture – transcend historical periods, Basil Germond frames contemporary seapower as a combination of components, including traditional naval power, post-modern conceptions of collective and civilian seapower, and the neo-modern phenomena of maritime territorialization and the naval arms race. By giving seapower a new conceptual definition, Seapower in the Post-modern World offers key analytical tools for understanding the stability of the global maritime order and seapower’s contribution to global leadership more broadly.