This book analyses a selection of challenges in the implementation and application of the 1982 UN Convention on the Law of the Sea (UNCLOS), focusing on several areas: international organizations, fisheries, security, preserving marine biodiversity, dispute settlement, and interaction with other areas of international law. UNCLOS has been described as the Constitution for the Oceans. It sets out the fundamental rights, obligations and jurisdictions of States regarding the access to, uses and management of the oceans and seas and their resources. It balances States’ diverse and sometimes conflicting interests, such as conflicting uses of space, against navigational interests and the protection of the marine environment. UNCLOS is the first global treaty to include comprehensive obligations on the protection and preservation of the marine environment, including the conservation of living marine resources. These are often common or cross-border challenges, which can onlybe addressed