By Giovanni Prete
New York—The high seas, the vast waters beyond national jurisdiction, cover nearly two-thirds of our planet. They are home to some of Earth's most mysterious and vital ecosystems, from migratory whales to deep-sea corals, and serve as a crucial regulator of the global climate by absorbing carbon and heat. Yet despite their importance, they remain largely unprotected, vulnerable to overfishing, deep-sea mining, plastic pollution, and the mounting impacts of climate change.
Unlike coastal waters, which fall under national control, the high seas encompass all areas of ocean beyond 200 nautical mile exclusive economic zones of any country.
These remote waters play a key role in maintaining planetary health. They support biodiversity hotspots, provide critical fisheries for millions of people and store carbon that would otherwise accelerate climate change. In short, the high seas are a lifeline for both marine ecosystems and human societies.
The high seas are often described as the “blue heart” of our planet. They are a major driver of Earth’s life‑support system. These waters are also home to unique ecosystems like hydrothermal vents, where life exists without sunlight, and massive migratory routes for whales, tuna, sharks and seabirds.
Fisheries from the high seas also provide a significant portion of the world’s seafood, feeding billions of people and sustaining global economies.
A 2018 study published in Science Advances revealed that nearly half of the high seas fishing would be economically unprofitable without heavy government subsidies, highlighting how little these industries are prepared to pay for their impacts.
Yet it isn’t just about fish. Scientists have discovered microbes in the high seas with properties that could unlock breakthroughs in medicine, including potential treatments for cancer and antibiotic resistance. The high seas are a frontier of undiscovered genetic resources and, as a frontier of science that humans are only beginning to explore.
For decades, the high seas were thought to be too vast and remote to be threatened by human activity. That has been shattered as we now know these waters face one of the most urgent ecological crises on the planet.
Overfishing remains the most immediate threat. Industrial fleets from wealthy nations dominate high sea fisheries, often targeting species like tuna, squid and deep-sea fish that take decades to mature. This not only depletes populations but also devastates ecosystems by disrupting predator‑prey balances.
Deep‑sea mining poses an emerging danger. Companies and governments are eyeing the seafloor for polymetallic nodules rich in cobalt, nickel and rare earth elements used in renewable energy technologies. However, scientists warn that mining could cause irreversible damage to fragile ecosystems that take millennia to form.
To address the threat, conservationists have called for a global moratorium on deep‑sea mining. A moratorium would allow more time for research and governance mechanisms to develop.
Plastic pollution is also pervasive in open ocean areas. Ocean currents converge into gyres that accumulate plastics, breaking down into microplastics and entering food chains. Scientific studies have found plastic fibers in deep‑sea trenches and inside marine animals in remote corners of the ocean.
Climate change further compounds these threats. The high seas are warming, becoming more acidic, and losing oxygen. These changes threaten coral reefs, plankton populations, and migratory species that rely on narrow temperature and oxygen windows.
One of the greatest challenges in protecting the high seas is governance. The high seas lie outside national boundaries; no single country has jurisdiction over them. Instead they are governed by a patchwork of international agreements. While UNCLOS lays the legal foundation for ocean governance, it has limitations. It primarily regulates navigation, territorial claims, and seabed mining through the International Seabed Authority. However, it offers little in the way of comprehensive biodiversity conservation.
The recent treaty negotiations on biodiversity beyond national jurisdiction, if fully ratified and implemented, could help meet global conservation targets such as protecting 30 percent of the ocean by 2030 - as agreed upon at the UN Biodiversity Conference in 2022. But challenges remain. At the last UN Ocean Conference in June, 18 countries ratified the agreement, bringing the total to 50. Ratification by at least 60 countries is required before the treaty can enter into force, and questions ling about financing, enforcement, and political will.
Still, the treaty marks a historic moment: for the first time, the global community has recognized that the high seas must be managed as a shared responsible resource.
The clock is ticking. Protecting the high seas will require international cooperation, stronger legal frameworks, and investment in science and surveillance. The decisions made in the coming years will determine whether this vast, vital part of our planet remains a refuge for wildlife and a buffer against climate disruption—or becomes yet another casualty of unsustainable exploitation.