This monograph investigates the spectacular renewal of the Byzantine navy under the founder of the Komnenian dynasty, Alexios I (1081-1118). It traces the development of the navy, its command structure, its warships, and numerical strength during Alexios I's reign and the reign of his immediate successors, John II (1118-1143) and Manuel I (1143-1180). The authors make extensive use of available written sources, engage with the archaeological context, and use advanced statistical analysis. The study underscores a critical transition: in 1081, Alexios inherited a navy in terminal decline from long-term neglect. The Komnenian reforms repositioned the fleet as a useful tool of Byzantine foreign policy during the era of the Crusades. Archaeological context confirms that maritime circulation in Byzantine waters changed significantly during this period.