Mare liberum

The terms international waters or trans-boundary 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.

International waters have no sovereignty, ergo is "Terra nullius" as no state controls it. All states have the freedom of: fishing, navigation, overflight, laying cables and pipelines, and research.

Oceans, seas, and waters outside of national jurisdiction are also referred to as the high seas or, in Latin, mare liberum (meaning free sea). The Convention on the High Seas, 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." The Convention on the High Seas was replaced by United Nations Convention on the Law of the Sea, which recognized Exclusive Economic Zones extending 200 nautical miles from the baseline, where coastal States have sovereign rights to the water column and sea floor as well as the natural resources found there.

Ships sailing the high seas are generally under the jurisdiction of the flag state (if there is one); however, when a ship is involved in certain criminal acts, such as piracy, 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.

...
Wikipedia