Orcas surface to blow air while surfacing with mountains illuminated by the sunset in the background.

Who rules the high seas? Outlaws and unknown sea creatures

Here are five things to know about international waters—a stretch of ungoverned ocean teeming with undiscovered life, underwater volcanoes, and modern-day pirates.

Orcas are one of many sea creatures that migrate through the high seas. A new U.N. treaty allows countries to create internationally-managed protected areas to protect species that live outside an individual country's jurisdiction. 
Photograph By BRIAN SKERRY, Nat Geo Image collection

The high seas are a vast no-man’s land of ungoverned ocean. 

Every country has jurisdiction over the waters extending 200 nautical miles from the shore, their Exclusive Economic Zone (EEZ). Beyond the EEZs lie international waters—and more than two-thirds of the world’s ocean. 

These uninhabited waters are rarely seen by people, but they’re teeming with life. More than 10 million species are found in the high seas, and millions of mysterious creatures unknown to science lie in its depths. 

That’s why a new United Nations (UN) treaty from March 2023 aims to govern the ungovernable, outlining how the world's countries could collectively protect a swath of ocean covering half the Earth’s surface.

Filled with underwater volcanoes and hidden species, traversed by pirates and outlaws—the high seas are unlike anywhere else on Earth. 

1. Modern-day pirates roam the high seas

Piracy is not a crime of the past. Today, it looks more like armed robbery or kidnapping for ransom according to Interpol, an international police organization, than it does Hollywood-style swashbuckling. Every year, modern-day pirates collect millions in ransoms. Less commonly, modern-day pirates hijack ships. 

Over 90 percent of the things we make and sell are transported by sea, and piracy occurs both close to shore and on the high seas. In 2020, there were 195 incidents of maritime piracy reported to the International Maritime Bureau. 

And pirates are not the only criminals seen on the high seas. Drugs and people are trafficked in these waters, chemicals and other types of waste are illegally dumped there, and fish are illegally taken out of the water. 

Some evading laws on the high seas have more altruistic aims. On board a vessel, crew follow the laws of the country their ship flies under, which is how the Dutch nonprofit Women on Waves provides abortion care to women living in countries where the procedure is outlawed.

2. The undiscovered depths offer mysteries for the imagination

Underwater mountain ranges, deep trenches, canyons, and hydrothermal vents are all found in the deep sea and are home to fish, whales, turtles, and corals. And while there are many species that scientists know live or migrate through the high seas, life here is largely a mystery. As many as 500,000 to 10 million species are thought to live, unknown to people, in the ocean. 

Only a tiny fraction of the high seas has been studied by scientists. And the greatest mysteries may lie in the hardest to reach habitats. 

For example, deep-sea corals are common here. The oldest-known living organism in the world, an 8,500-year-old coral, can be found in international waters. 

And some of these undiscovered species have medicinal value. Compounds found in deep-sea sponges are being tested for their ability to fight cancer and chronic health conditions. 

Currently, less than one percent of the high seas is protected, but the UN’s new treaty allows countries to collectively create marine protected areas (MPAs) that can protect portions of the high seas from overfishing and shipping lanes.

3. Fishing there is a source of passionate controversy 

Fishing has been described as one of the world’s most dangerous jobs, and whether it should be allowed on the high seas at all is hotly debated. 

A study from 2018 showed fishing on the high seas was unprofitable, just over half of it propped up by government subsidies. About 3,600 vessels are estimated to fish on the high seas, just six percent of all fishing activity. But fishing here has a disproportionate impact on sustainability and human rights. Fishing vessels often use a method called deep-sea bottom trawling where huge nets scoop up everything in their path—commercially sold fish, but also coral reefs and rare or threatened marine animals. 

Some countries, China for example, use the high seas to compensate for the lack of fish in their own depleted waters. Scientists estimate that about 70 percent of fish in countries’ waters spend some of their life in the high seas, and one study published in 2015 found that if the high seas were closed to fishing, nearby fish stocks in EEZs might benefit from large fish populations spilling over into their territory. The effect could potentially increase commercial fish in territorial waters by 18 percent.

(Learn more about overfishing.)

4.  They are the site of serious crimes

Thousands of miles from land, the high seas provide cover for crimes like forced labor and murder. 

A New York Times investigation published in 2015 recounted stories of violence, enslavement, harsh punishments, and worse for laborers often tricked into working aboard fishing vessels and detained for years. Fishing boats on the high seas use ships called long-haul vessels. They park over open ocean for months to years and are resupplied by ships that deliver supplies and pick up caught fish, allowing the parked vessel to hide from oversight. 

Another investigation published in 2019 by the Associated Press found many of these fish caught by slave labor end up eaten in the United States.

Labor activists and law enforcement have begun using satellites to monitor ships on the high seas for suspicious behavior consistent with forced labor practices. 

5. They provide valuable carbon sequestration

Marine life like plankton and algae are responsible for storing vast amounts of carbon dioxide emissions in the high seas. Every year they draw 1.5 billion metric tons of carbon dioxide out of the atmosphere, according to a report published in 2014.

That same report suggested that the high seas pull so much carbon out of the air, it’s worth an estimated $148 billion. Since that carbon is absorbed by plants and animals that store carbon in their bodies or transfer it to the seafloor, some scientists think all fishing on the high seas should be banned. 

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