The oceans provide many vital ecosystem services for humankind, but the health of the world’s seas is in serious decline. The protection of the marine environment has emerged as one of the most pressing challenges for the international community. An effective solution depends upon the cooperation of all states towards achieving agreed objectives. International law plays a vital role in this process. This book provides a critical assessment of the international legal instruments that have been negotiated for the protection of the marine environment and identifies key trends in global ocean governance. Starting with a detailed analysis of the United Nations Convention on the Law of the Sea, the book explains and evaluates the main global and regional treaties and related instruments that seek to prevent, reduce, and control damage to the marine environment caused by navigation, seabed exploitation, fishing, dumping, geo-engineering, and land-based activities, as well as emerging pressures such as ocean noise, ocean acidification, and climate change. The book demonstrates how international institutions have expanded their mandates to address a broader range of marine environmental issues and to promote an ecosystems approach to regulation. It also discusses the development of diverse regulatory tools to address anthropogenic impacts on the marine environment and the extent to which States have adopted a precautionary approach in different maritime sectors. Whilst many advances have been made, the book highlights the need for greater coordination between international institutions, as well as the desirability of developing stronger enforcement mechanisms for international environmental rules.