As pointed out in the Foreword, the United Nations Convention on the Law of the Sea (the Convention) is, by any measure, a remarkable document, which for the first time provides a comprehensive framework of governance for a large part of the world ocean. It covers such issues as delimitation, environmental impact and management, scientific research, economic and commercial issues, and technology transfer and provides a regime for the peaceful settlement of disputes. The resolution of disputes is especially important, given that there are 151 coastal States, all with sovereign rights to the adjacent seas and shelf. Under the Convention, those rights cover a total area of about 60 million km2 or around 20% of the world ocean within the 200-nauticalmile (M) limit. But there is perhaps an additional 5% (15 million km2) which lies beyond the 200-M limit, to which sovereign rights may also extend under the terms of the Convention. Up to 54 coastal States may be able to claim extensions of their continental shelf beyond 200 M (figure 1.1). What is intended is that over the next 10 years or so, nations will document and lay claim to an area of around 75 million km2, equal to more than half the Earth's land surface. Viewed against the background of human history and land conquest extending over thousands of years, the magnitude of the undertaking is extraordinary. What is also remarkable is the key role that science and technology will play. Science and technology have always played a role in exploration and documentation of the oceans in the past. The development of an accurate chronometer by Harrison in the 18th century was critical to developing an accurate means of establishing longitude (Sobel, 1995). This in turn made it possible to accurately chart the oceans for the first time, which then enabled nations to lay claim to newly explored areas, establish trade routes, document marine hazards, and exploit ocean resources. Parts of the world's territorial sea baselines are and will continue to be based on 19th-century data. As will be evident from this book, such data are sufficiently important in some areas that we have felt it necessary to document just how those "historical data" were gathered so that we can establish their reliability.