The LOSC devotes Part VII to the high seas. Under Article 86, the high seas are defined as:
all parts of the sea which are not included in the EEZ, in the territorial sea or in the internal waters of a State, or in the archipelagic waters of an archipelagic State. Where a coastal State has established its EEZ, the landward limit of the high seas is the seaward limit of the EEZ. Where the coastal State has not claimed its EEZ, the landward limit of the high seas is the seaward limit of the territorial sea. In this case, the seabed of the high seas is the continental shelf of the coastal State up to the limit fixed by the international law of the sea. The seabed and subsoil beyond the outer limits of the continental shelf are the Area, which is the common heritage of mankind. The superjacent waters above the Area are always the high seas. Where the continental shelf extends beyond the limit of 200 nautical miles, the superjacent waters and the airspace above those waters are the high seas under Article 78 of the LOSC.
The high seas are governed by the principle of freedom. However, it is not suggested that there is no legal order on the high seas. The order on the high seas is essentially ensured by the principle of the exclusive jurisdiction of the flag State. Thus this principle and its exceptions become principal issues in the international law governing the high seas.
The Area, namely ‘the seabed and ocean floor and subsoil thereof, beyond the limits of national jurisdiction’, is governed by the principle of the common heritage of mankind. As will be seen, this principle is an important innovation in the law of the sea as it introduces the concept of ‘mankind’ as an emerging actor in international law. The principle of the common heritage of mankind will provide a touchstone to consider the question of whether and to what extent international law in the twenty-first century is moving towards an international law for mankind, which is beyond the State-to-State system. Against that background, this chapter focuses on legal regimes governing the high seas and the Area.