International waters

The terms international waters or transboundary waters apply where any of the following types of bodies of water (or their drainage basins) transcend international boundaries: oceans, large marine ecosystems, enclosed or semi-enclosed regional seas and estuaries, rivers, lakes, groundwater systems (aquifers), and wetlands.^[1]

International waters are the areas shown in dark blue in this map, i.e. outside exclusive economic zones which are in light blue.

"International waters" is not a defined term in international law. It is an informal term, which sometimes refers to waters beyond the "territorial sea" of any country.^[2] In other words, "international waters" is sometimes used as an informal synonym for the more formal term high seas or, in Latin, mare liberum (meaning free sea).

International waters (high seas) do not belong to any state's jurisdiction, known under the doctrine of 'mare liberum'. States have the right to fishing, navigation, overflight, laying cables and pipelines, as well as scientific research.

The Convention on the High Seas, signed in 1958, which has 63 signatories, defined "high seas" to mean "all parts of the sea that are not included in the territorial sea or in the internal waters of a State" and where "no State may validly purport to subject any part of them to its sovereignty."^[3] The Convention on the High Seas was used as a foundation for the United Nations Convention on the Law of the Sea (UNCLOS), signed in 1982, which recognized exclusive economic zones extending 200 nautical miles (230 mi; 370 km) from the baseline, where coastal states have sovereign rights to the water column and sea floor as well as the natural resources found there.^[4]

The high seas make up 50% of the surface area of the planet and cover over two-thirds of the ocean.^[5]

Ships sailing the high seas are generally under the jurisdiction of the flag state (if there is one);^[6] however, when a ship is involved in certain criminal acts, such as piracy,^[7] any nation can exercise jurisdiction under the doctrine of universal jurisdiction. International waters can be contrasted with internal waters, territorial waters and exclusive economic zones.

UNCLOS also contains, in its part XII, special provisions for the protection of the marine environment, which, in certain cases, allow port States to exercise extraterritorial jurisdiction over foreign ships on the high seas if they violate international environmental rules (adopted by the IMO), such as the MARPOL Convention.^[8]

International waterways

Komárno in Slovakia is an inland port on the Danube River which is an important international waterway.

Several international treaties have established freedom of navigation on semi-enclosed seas.

The Copenhagen Convention of 1857 opened access to the Baltic by abolishing the Sound Dues and making the Danish Straits an international waterway free to all commercial shipping. Separately, the Royal Ordinance of 1999 regulates the access of foreign warships to Danish waters.^[9]^[10]^[11]
Several conventions have opened the Bosphorus and Dardanelles to shipping. The latest, the Montreux Convention Regarding the Regime of the Turkish Straits, maintains the straits' status as an international waterway.

Other international treaties have opened up rivers, which are not traditionally international waterways.

The Danube River is an international waterway so that Germany and Croatia, as well as landlocked Austria, Slovakia, Hungary, Serbia and Moldova can have secure access to the Black Sea.

Disputes over international waters

Atlantic Ocean – the main zone of sea transport in the 15th–20th centuries.

Current unresolved disputes over whether particular waters are "International waters" include:

The Arctic Ocean: While Canada, Denmark, Russia and Norway all regard parts of the Arctic seas as national waters or internal waters, most European Union countries and the United States officially regard the whole region as international waters. The Northwest Passage through the Canadian Arctic Archipelago is one of the more prominent examples, with Canada claiming it as internal waters, while the United States and the European Union considers it an international strait.^[12]
The Southern Ocean: Australia claims an exclusive economic zone (EEZ) around its Antarctic territorial claim. Since this claim is only recognised by four other countries, the EEZ claim is also disputed.
Area around Okinotorishima: Japan claims Okinotorishima is an islet and thus they should have an EEZ around it, but some^[quantify] neighboring countries claim it is an atoll and thus should not have an EEZ.
South China Sea: See Territorial disputes in the South China Sea. Some countries^{[note 1]} consider (at least part of) the South China Sea as international waters, but this viewpoint is not universal. Notably, China, which opposes any suggestion that coastal States could be obliged to share the resources of the exclusive economic zone with other powers that had historically fished there, claims historical rights to the resources of the exclusive economic zones of all other coastal States in the South China Sea.^{[citation needed]}

In addition to formal disputes, the government of Somalia exercises little control de facto over Somali territorial waters. Consequently, much piracy, illegal dumping of waste and fishing without permit has occurred.