Because the sea has been an essential means of transport since ancient times, and even today merchant shipping still carries 95 per cent (by weight) of all exports, the rules governing the use of the sea (including its resources and environment) are one of the principal subjects of international law. The law is a mixture of treaty and established or emerging customary international law, the customary law having developed over centuries. The first successful attempt to codify the law was the 1958 UN Conventions on the Law of the Sea, but the most important aspects of the law are now set out in the UN Convention on the Law of the Sea 1982 (in this chapter, ‘the Convention’ or ‘UNCLOS’). For those parties to the Convention that were parties to the 1958 Conventions, the 1982 Convention replaces them. Although between thirty-seven and sixty-two states are still listed as parties to the four 1958 Conventions, in many cases they are now bound by the 1982 Convention, which entered into force on 16 November 1994, and now has 148 parties. As most of the Convention's provisions represent customary international law, even non-parties, such as Iran and the United States, are already bound by those provisions albeit as customary international law.