Baselines: Defining Maritime Zones & Internal Waters

Understanding the Baseline

A baseline is a fundamental reference line, typically drawn along a nation's coastline. Its primary purpose is to serve as the starting point for measuring the outer limits of a state's various maritime zones, including its territorial sea and exclusive economic zone (EEZ).

Normally, this baseline aligns with the low-water mark along the coast, representing the lowest tide level. This method is used for relatively smooth and stable coastlines.

Straight Baselines: Special Cases

In specific geographical situations, an alternative approach known as straight baselines may be adopted. This occurs when the coastline is highly indented, features numerous islands close to the shore, or exhibits significant instability due to geological factors.

Internal Waters: Full Sovereignty

Internal waters are defined as all waters situated on the landward side of the established baseline. These are the closest maritime areas to a state's land territory.

A coastal state exercises full sovereignty over its internal waters, akin to its land territory. This means it has complete control and jurisdiction over these areas.

A crucial aspect of internal waters is that there is no right to innocent passage through them. This means foreign vessels cannot pass through without the explicit permission of the coastal state.

Territorial Sea: Limited Sovereignty

The territorial sea extends seaward from the baselines up to a maximum distance of 12 nautical miles (nm). This zone is a direct extension of the state's sovereignty.

However, the coastal state's rights in the territorial sea are subject to a significant limitation: the right to innocent passage. Foreign vessels are generally allowed to pass through, provided their passage is not prejudicial to the peace, good order, or security of the coastal state.

Contiguous Zone: Preventive Rights

The contiguous zone is an area adjacent to and extending beyond the territorial sea. It stretches seaward up to 24 nm from the baselines, creating an intermediary area between the territorial sea and the high seas.

In this zone, the coastal state has specific rights to prevent and punish infringement of its fiscal, immigration, sanitary, and customs laws. These laws must have been violated within its territory or territorial sea.

Exclusive Economic Zone (EEZ): Resource Rights

Each coastal state has the right to claim an Exclusive Economic Zone (EEZ). This zone extends beyond and adjacent to its territorial sea, reaching up to 200 nm from its baselines.

Within its EEZ, a coastal state holds sovereign rights primarily for the purpose of exploring, exploiting, conserving, and managing natural resources. This includes both living and nonliving resources found in the seabed, subsoil, and overlying waters.

It is important to note that the EEZ primarily grants resource rights. Unlike the territorial sea and contiguous zone, it does not give a coastal state the right to prohibit or significantly limit freedom of navigation or overflight for other nations, with only limited exceptions.

Continental Shelf: Geological Extension

A continental shelf represents the natural geological extension of a continent beneath the ocean. It extends from the coastline out to a distinct drop-off point known as the shelf break.

Beyond the shelf break, the seafloor descends more steeply into the deep ocean basin, forming what is called the continental slope. This geological feature is distinct from the legal maritime zones, though related.

High Seas: Common Heritage

The areas of the ocean surface and the water column that lie beyond the outer limits of a state's EEZ are collectively referred to as the high seas. These vast areas are beyond any single national jurisdiction.

States are permitted to conduct various activities in the high seas, provided these activities are for peaceful purposes. This includes activities such as transit, marine science research, and undersea exploration, all subject to international law.