The high seas represent the vast expanse of the ocean that lies beyond the direct control of any single nation. This immense, interconnected body of water covers nearly two-thirds of the world’s ocean surface, making it the largest shared space on Earth. It operates as a global commons, influencing planetary systems and supporting diverse life forms. Understanding this domain helps comprehend global ecosystems and human interactions with the marine environment.
Defining the High Seas
The high seas are defined as all parts of the sea not included in the exclusive economic zone (EEZ), territorial sea, internal waters of a state, or archipelagic waters of an archipelagic state. This means they begin where national jurisdiction ends, typically beyond 200 nautical miles from a country’s coastline. Within these 200 nautical miles, coastal nations have sovereign rights over natural resources and certain economic activities within their EEZ. The seabed and subsoil beneath the high seas are also part of this international area, known as the Area.
Governance and Jurisdiction
The high seas are governed by a framework of international law, with the United Nations Convention on the Law of the Sea (UNCLOS) serving as the foundational treaty. This convention, adopted in 1982, establishes a legal order for the oceans. It designates the high seas as an area open to all states, whether coastal or landlocked, under the principle of freedom of the high seas. This principle allows for activities such as navigation, overflight, fishing, and scientific research.
No single nation holds sovereignty over the high seas; they are considered a global common. Activities conducted in these waters are primarily regulated by the “flag state,” which is the country where a vessel is registered. This system aims to ensure orderly conduct while upholding freedom of access for all nations.
Ecological and Economic Importance
The high seas play a role in maintaining the planet’s ecological balance. They host biodiversity, including migratory species like whales, sharks, and tuna that traverse vast distances across ocean basins. These waters also act as a carbon sink, absorbing carbon dioxide from the atmosphere and helping to regulate global climate patterns. Ocean currents originating in these areas distribute heat and nutrients worldwide, influencing weather systems and supporting marine ecosystems far beyond their immediate boundaries.
Economically, the high seas are also valuable. They serve as major shipping lanes, facilitating over 80% of global trade and connecting continents through maritime transport. These waters contain fishing grounds, which provide a portion of the world’s seafood supply. There is also potential for deep-sea mineral resources, such as polymetallic nodules, rich in metals like manganese, nickel, copper, and cobalt. The high seas offer opportunities for scientific research, advancing understanding of ocean processes, marine life, and climate change.
Human Activities and Environmental Pressures
Various human activities occur on the high seas, with environmental consequences. Commercial shipping, while facilitating global trade, contributes to marine pollution through oil spills, wastewater discharge, and noise pollution from large vessels. Industrial fishing operations, including bottom trawling, exert pressure on fish stocks, leading to overfishing and depletion of many species. Bottom trawling can cause damage to delicate deep-sea habitats and benthic ecosystems.
Emerging activities like deep-sea mining exploration pose new threats to the unique ecosystems of the deep seabed. These operations could disturb habitats and release sediment plumes that impact marine life. Beyond direct human actions, the high seas are impacted by broader environmental changes. Marine pollution from land-based sources, such as plastic waste, accumulates in remote ocean gyres, forming patches of debris. Climate change also affects these waters through ocean warming, which alters marine habitats and species distribution, and ocean acidification, which threatens calcifying organisms like corals and shellfish by reducing the pH of seawater.
International Conservation Efforts
Recognizing the shared nature and vulnerability of the high seas, international conservation efforts are underway to ensure their protection and sustainable management. A development is the Biodiversity Beyond National Jurisdiction (BBNJ) Agreement, also known as the High Seas Treaty, adopted in 2023. This agreement provides a framework for establishing marine protected areas on the high seas and regulating activities to conserve marine biodiversity. It aims to address gaps in existing governance by promoting cooperation and integrated management.
Regional Fisheries Management Organizations (RFMOs) also play a role in managing specific fish stocks across multiple national jurisdictions and the adjacent high seas. These organizations set quotas, regulate fishing gear, and monitor compliance to prevent overfishing and promote sustainable practices. Effective conservation of the high seas requires ongoing international cooperation, scientific research, and the implementation of management measures. These actions help safeguard this global common for future generations.