Sea areas nearby nations are divided into maritime zones that represent internationally recognized legal boundaries. The most important marker from which other boundaries are derived is the baseline, which is the mean low tide line. Many seaports are located in close proximity to the baseline. From this marker, three areas can be identified by their level of sovereignty:
- Sovereign waters. Water areas over which the state has complete jurisdiction, implying that no foreign vessel may navigate without permission. This includes national waters, such as rivers and lakes. Each coastal nation can claim a 12 nautical mile area from its baseline, a territorial sea over which it exercises full sovereignty of the waters, seabed, and air space. A foreign ship may have the right of “innocent passage”, subject to the state’s rules and regulations. Archipelagic waters (not shown) are sovereign waters enclosed within a group of islands belonging to the same nation. Indonesia and the Philipines are the most notable examples of states with substantial archipelagic waters that allow free navigation along defined passages, such as the Strait of Malacca.
- Areas outside of sovereignty but within national jurisdiction. The contiguous zone is a 12-nautical mile area extending beyond the territorial sea over which a state can prevent any potential infringement of its laws and regulations. This can involve the seizure of cargo and people that are judged to be in infraction. The exclusive economic zone (EEZ) extends 200 nautical miles from the baseline and represents an area over which a state has sovereignty for exploiting natural resources, such as fishing and seabed mining. It also has the right to establish artificial structures, such as islands and rigs. Foreign ships have the right of passage without being subject to the state’s rules and regulations. The continental shelf represents an area, often extending beyond the EEZ, with relatively shallow waters over which a state has the right over seabed resources.
- Areas beyond national jurisdiction. Often labeled as the high seas, which represent international waters where no state has sovereignty and jurisdiction over water and seabed resources. About 64% of the oceans are within this category. Although not subject to sovereignty, the resources of the high seas are managed by the International Seabed Authority (ISA).