This publication presents the ongoing developments in the maritime environment and shows how they will impact the future submarine operating environment. The changes are triggered both by intensive and commercial activities around the maritime domain and by the dynamic and rapidly developing nature of war at sea. It is critical for NATO nations and their leaders to consider these factors while analyzing the future role of submarines and determining the operational needs that role will fill. In doing so, NATO nations and their allies will be better prepared to face the consequences of present developments and to maintain an edge in an environment shaped by them.The scope of this publication shall include, but not be limited to, changes in the maritime environment that alter future the submarine operating environment. It is important to consider both critical worldwide developments and specific regional changes with ranges limited to certain areas or seas in this discussion. This book also highlights some aspects of the security environment and discusses factors that may have an impact on conducting naval operations in the future.The study is an appealing attempt to cover, in a synthetic way, a very complex, multithreaded and multidisciplinary issue. This is important insofar as it is of great practical significance .What deserves to be emphasized is the author’s wide horizon of observation of the environment, efficiently navigating through the maze of various problems. The main, however, value of the study is the capture and meaningful ordering of various factors that form the contemporary and future submarine operating environment.