05/24/2026
The US just expanded its territory beneath the ocean by nearly 386,000 square miles (1 million square kilometers).
That is an underwater area almost 60% the size of Alaska – or larger than two Californias combined.
But this is not new land rising out of the sea.
The expansion involves something called the Extended Continental Shelf (ECS), a legal concept under international maritime law that gives countries rights to the seabed and resources beneath it beyond the standard 200 nautical mile limit.
In simple terms, countries can claim parts of the ocean floor if they can scientifically prove that the seabed is a natural extension of their continental landmass.
To do that, the U.S. spent more than 20 years collecting evidence across the Arctic, Atlantic, Pacific, Bering Sea, Gulf of Mexico, and around the Mariana Islands.
Scientists conducted 40 ocean missions using sonar mapping, seismic profiling, sediment sampling, and deep-sea geological analysis to map underwater terrain in extraordinary detail.
Researchers even discovered entirely new seamounts and geological structures during the process.
The result was a massive scientific submission defining the outer limits of the U.S. continental shelf under the framework of the United Nations Convention on the Law of the Sea (UNCLOS).
Even though the United States has never formally ratified UNCLOS, it still follows many of its rules and uses them to support maritime claims.
The move does not give the U.S. ownership of the ocean water itself, and it does not expand fishing rights or territorial waters.
Instead, it gives the U.S. rights to resources in the seabed and subsoil, including oil, natural gas, rare minerals, and other geological resources.
It also expands the country’s ability to regulate environmental activity on parts of the seafloor.
The claim could become increasingly important in the future as countries compete for critical underwater resources tied to energy production, technology, and climate-related industries.
But it also raises geopolitical questions.
Some regions overlap with potential claims from Canada and exist near sensitive Arctic territory involving Russia.
At the same time, scientists and policymakers warn that expanding access to deep-sea resources could increase pressure on fragile marine ecosystems that remain poorly understood.
In many ways, this is part of a growing global race to map and define the hidden geography beneath the oceans.
