‘The dark oceans were the womb of life: from the protecting oceans life emerged’. 1 As can be seen in the words of Arvid Pardo, the Ambassador for Malta, it would be no exaggeration to say that a sound marine environment provides the foundation for all life. Hence rules of international law governing the oceans are of particular importance in the international community. This book will seek to provide readers with a systematic overview of the international law of the sea as an inseparable part of public international law. In the present author’s view, rules of the international law of the sea must be examined from a dual viewpoint, namely the reconciliation of interests between States and the protection of community interests. This book is thus divided into two parts. Part I, which consists of Chapters 1 to 6 , involves international law governing jurisdictional zones at sea. In the international law of the sea, the oceans are divided into several jurisdictional zones, namely internal waters, territorial sea, archipelagic waters, the contiguous zone, the exclusive economic zone (EEZ), the continental shelf, the high seas and the Area. In principle, the law of the sea regulates human activities in the ocean according to these jurisdictional zones. Thus Part I will examine the rules of international law concerning each jurisdictional zone focusing on the reconciliation of various interests between States. At the same time, limits and delimitation of marine spaces will also be discussed in this part.