No one owns the oceans as a whole. Under international law, most of the sea is treated as a shared space, and the rules come mainly from the United Nations Convention on the Law of the Sea (UNCLOS), adopted in 1982. Most countries are parties to it, though the United States has signed but not ratified it, while still generally following its rules as customary law.
How the ocean is divided:
- Territorial sea (up to 12 nautical miles from the coast): The coastal country has sovereignty here, much like on land, but foreign ships have a right of “innocent passage.”
- Contiguous zone (up to 24 nautical miles): The coastal country can enforce customs, immigration, and sanitary laws.
- Exclusive Economic Zone, or EEZ (up to 200 nautical miles): The coastal country has exclusive rights to fish, drill for oil and gas, and use the resources, but others can still sail and fly through freely.
- Continental shelf: A country can claim rights to the seabed and its resources beyond 200 nautical miles in some cases, if the shelf extends that far and the claim is approved by a UN commission.
- High seas (beyond all national zones): These belong to no one. All countries have freedom of navigation, fishing, overflight, and scientific research, though with obligations to protect the marine environment.
- The Area (the deep seabed beyond national limits): Its mineral resources are considered the “common heritage of mankind” and are managed by the International Seabed Authority.
About 60 percent of the world’s ocean falls under the high seas, so most of the ocean is legally shared. In 2023, countries also agreed on a High Seas Biodiversity treaty to help protect marine life in these waters.
Disputes still arise, especially over overlapping EEZ claims and islands, such as in the South China Sea, but the legal principle is that the sea is a shared resource rather than something anyone owns outright.
1 nautical mile = 1.852 kilometres (exactly, by international agreement).
So the zones I mentioned earlier work out roughly as:
- 12 nautical miles (territorial sea) ≈ 22.2 km
- 24 nautical miles (contiguous zone) ≈ 44.4 km
- 200 nautical miles (EEZ) ≈ 370.4 km
A nautical mile is a bit longer than a regular (statute) mile, which is about 1.609 km. It’s based on one minute of latitude along the Earth’s surface, which is why it’s used in sea and air navigation.