The United Nations Convention on the Law of the Sea (UNCLOS) entered into force in 1994 and has since been ratified by about 160 states, including all the Member States of the EU and the EU itself. The Convention defines the rights and duties of national states with regard to the use of the seas. UNCLOS consolidates customary international law and various Conventions previously adopted by the international community. This Treaty, the most comprehensive ever concluded, is often referred to as ‘the constitution for the seas’. This Commentary focuses particularly on the interaction between UNCLOS and the European legal order, for example in the field of the prevention or the reduction of environmental pollution and the fair distribution of natural resources.