Areas of the ocean that lie beyond any country’s national jurisdiction. They make up about 60% of the ocean’s surface and are largely unregulated.
Origin of the term: The phrase “high seas” dates back to the 14th–15th century in English maritime law. “High” here means “open” or “beyond jurisdiction” (not close to land or under any country’s control), as opposed to “territorial seas” near the coast.
Modern meaning: The High Seas are the areas of the ocean that lie beyond any single country’s national waters.
Because they were historically unregulated, they have been vulnerable to overfishing, pollution, and other threats. In January 2026, the High Seas Treaty (BBNJ Agreement) entered into force to help protect marine biodiversity in these international waters.
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