Oceans & international law

High Seas

Meaning statusEstablishedSource recordDirect document linkedWhy these are different

Definition

The high seas are the parts of the sea that are not included in the exclusive economic zone, territorial sea, or internal waters of any state, as defined in Article 86 of the UN Convention on the Law of the Sea. Covering about two-thirds of the ocean, they belong to no country; the 2023 BBNJ Agreement, which entered into force in January 2026, establishes the first comprehensive framework for conserving marine biodiversity in these areas.

References

OceanCareHigh Seas Treaty — BBNJ Agreement adopted 19 June 2023, in force 17 January 2026; high seas ~64% of the ocean; MPAs, EIA, genetic-resource benefit-sharing

scale and new legal regime

Marine Policy (ScienceDirect)Critical appraisal of the BBNJ agreement — high seas defined in UNCLOS Article 86 as areas beyond national jurisdiction

legal definition

Overview

What it means

The high seas are the planet's largest commons — and historically its weakest governed. Freedoms of navigation and fishing applied, but no mechanism existed to create marine protected areas or require environmental impact assessment in international waters. The BBNJ Agreement changes this with provisions for MPAs, EIA, benefit-sharing of marine genetic resources, and capacity building.

How it is used

The concept structures the Law of the Sea, fisheries governance, deep-seabed mining debates, and the 30x30 ocean-protection target.

Why it matters

Half the planet's surface cannot be protected without a legal regime for the high seas; one now exists for the first time.