New scenarios present in the sea require new legal and political approaches, because the rules governing these spaces have been out of place or new rules have arisen that require mitigation. Old aspects require new interpretations without prejudice of new uses not foreseen or contemplated in the frame of the Law of the Sea. In fact, many frustrations have been raised in this framework, because the Law of the Sea has been unable to give an answer to some of the expectations for which the United Nations Law of the Sea Convention was adopted. New doctrines and new interpretations have appeared to such an extent that experts hardly know whether they are going to lead them to a new system or to the modification of the present one. The part of the Law of the Sea that has been the most developed, but which has provoked greater problems at the same time has been the delimitation of maritime spaces, which has generated a new concept of states’ frontiers beyond the classical conception. This book analyses different aspects of marine delimitation. Concerning the environment, the authors focus on the analysis on the climatic change, where they have found a world of possibility to be explored. Everybody is aware that seas and oceans are the greatest dumping grounds of CO2 on Earth. Readers will easily understand that the global warming taking place is due to the lack of absorption by seas and oceans. Even more so, this provokes more storms and marine upheavals, which in turn cause the carbon deposited on the seabed to be moved and transferred to the surface, and this prevents a greater absorption of the atmospheric CO2. Finally, this book studies some social, economic and humanitarian problems affecting these maritime spaces; one has to take into consideration the new uses, the new frauds and the new dimensions that have created problems which did not exist before. In this case, the book explores sustainable fisheries and marine biodiversity, the management of marine living resources, the trafficking of persons and smuggling of migrants, the problems concerning Antarctica and the protection of underwater cultural heritage.