High Seas

Geography glossary

Also called: Areas beyond national jurisdiction · Topic: Oceans: Hydrological Cycle, Relief of the Ocean Floor, Temperature and Salinity · NCERT: Beyond NCERT

Meaning

The high seas are all parts of the ocean that lie beyond every country's exclusive economic zone (EEZ), territorial sea and internal waters. No country owns them. All states, including landlocked ones, may use them for peaceful purposes, but they must also help conserve their living resources.

They matter because they cover roughly two-thirds of the ocean. Shared fish stocks, deep-sea minerals and the new BBNJ Agreement ("High Seas Treaty") all depend on how this open space is governed.

Explanation

How the high seas are defined: the ladder of maritime zones

  • UNCLOS (1982), the UN Convention on the Law of the Sea, divides the sea into zones. A coastal country's control gets weaker the farther out a zone lies:
  • Territorial sea: up to 12 nautical miles. The country has full sovereignty (complete ownership and control).
  • Contiguous zone: up to 24 nautical miles. The country can enforce customs, immigration and health laws.
  • EEZ: up to 200 nautical miles. The country has rights over the fish, oil and other resources, but not full ownership of the water.

  • High seas: everything beyond the EEZ. No country has jurisdiction there.

  • The high seas are the water column: the sea surface and the water below it. The seabed under the high seas has its own legal name, "the Area".

  • "Areas beyond national jurisdiction" (ABNJ) is the wider term. It means the high seas plus the Area together.

The freedoms of the high seas

  • Every state, coastal or landlocked, can enjoy these freedoms:
  • navigation (ships sailing through)
  • overflight (aircraft flying over)
  • laying submarine cables and pipelines
  • fishing
  • marine scientific research

  • building artificial islands and installations allowed by international law

  • No state can claim sovereignty over any part of the high seas.

  • The freedoms are not unlimited. Each state must respect the rights of other states, use the sea for peaceful purposes and cooperate to conserve fish stocks.

Who keeps order: the flag state

  • No country rules the high seas, so the law follows the ship.
  • A ship on the high seas is under the law of the country whose flag it flies (the flag state).
  • So India regulates its own boats there. This is why India issued Guidelines for Sustainable Harnessing of Fisheries in the High Seas by Indian-Flagged Fishing Vessels, 2025.

  • Indian boats also need a Letter of Authorisation (LoA) for high-seas fishing. The Vice President launched it.

  • Regional fisheries bodies manage fish that move across many zones. In the Indian Ocean, the IOTC (Indian Ocean Tuna Commission) manages tuna for all countries fishing there.

The governance problem and the BBNJ answer

  • Why open access causes damage:
  • Everyone can fish, but no single country is responsible for the stock.
  • Each fleet has a reason to catch more before others do, so shared stocks get overfished.

  • For example, the IOTC has found yellowfin tuna to be overfished and subject to overfishing. Overfished means too few fish are left. Subject to overfishing means fish are still being caught faster than they can breed back.

  • BBNJ Agreement ("High Seas Treaty"):

  • It was adopted in June 2023 under UNCLOS and has been in force since 17 January 2026.
  • It provides for:
    • marine protected areas on the high seas, which are needed for the 30x30 target (protecting 30% of the planet's land and sea by 2030)
    • environmental impact assessments before harmful activities
    • sharing the benefits from marine genetic resources (useful genes from sea life, for example for medicines)
    • capacity-building, meaning training and technology for poorer countries
  • India signed it in 2024.

Where it occurs

  • World: the open ocean beyond 200 nautical miles from coasts, in the Pacific, Atlantic, Indian, Southern and Arctic Oceans. It makes up about two-thirds of the world ocean.
  • North Pacific Gyre: a huge ring of currents. It gathers the Great Pacific Garbage Patch between Hawaii and California, a pollution problem no single country can solve alone.

  • Mid-oceanic ridges and abyssal plains: most of these features lie under the open ocean, so their seabed falls in the Area rather than in any country's zone.

  • Indian Ocean beyond India's EEZ:

  • Tuna migration routes pass near the Andaman & Nicobar Islands and Lakshadweep. The same tuna stock moves between India's EEZ and the high seas.
  • Budget 2025-26 announced an enabling framework for sustainable fishing in the Indian EEZ and the High Seas, with a special focus on A&N and Lakshadweep.

  • The high-seas LoA was launched together with the Odisha Deep Sea Fishing Mission document.

  • Seabed below the Indian Ocean high seas (the Area):

  • Central Indian Ocean Basin: India holds an ISA contract here for about 75,000 sq km of polymetallic nodules (lumps rich in manganese, nickel, cobalt and copper). India became the first "pioneer investor" in 1987.

  • Indian Ocean ridges: India holds an ISA contract here for polymetallic sulphides, which form around hydrothermal vents.

  • Who runs what:

  • The Department of Fisheries (Ministry of Fisheries, Animal Husbandry & Dairying) regulates Indian fishing boats.
  • The IOTC manages tuna across the Indian Ocean.
  • The International Seabed Authority (ISA) manages seabed minerals in the Area.

Don't confuse with

  • Exclusive economic zone (EEZ): in the EEZ (up to 200 nautical miles), the coastal state alone controls the resources. Indian boats there need an Access Pass through ReALCRaft, and foreign vessels are not eligible. On the high seas, no state controls the resources.
  • The Area (international seabed): the high seas are the water. The Area is the seabed and what lies under it beyond national limits. Its minerals are the "common heritage of mankind" and are managed by the ISA. Deep-sea mining comes under the ISA, not under the freedom of the high seas.
  • Extended continental shelf: under UNCLOS Art. 76, a country's shelf can reach up to 350 nautical miles. That gives it rights over the seabed only. The water above the shelf beyond 200 nautical miles is still high seas.
  • Territorial sea: a coastal state has full sovereignty there, up to 12 nautical miles. The high seas are the opposite case: no state has any sovereignty.

Prelims Hooks

  • The high seas begin at the outer edge of the EEZ (200 nautical miles). No state can claim sovereignty over them, and landlocked states enjoy the same freedoms.
  • On the high seas, a ship comes under the law of its flag state. India's 2025 Guidelines apply to Indian-flagged fishing vessels.
  • BBNJ Agreement: adopted June 2023, in force since 17 January 2026, made under UNCLOS. India signed it in 2024.
  • ABNJ = high seas (water) + the Area (seabed). Trap: "Polymetallic nodules in the Central Indian Ocean Basin are governed by the high-seas fishing freedoms." This is FALSE. They come under the ISA.
  • Trap: "A country with an extended continental shelf also controls the waters above it beyond 200 nautical miles." This is FALSE. Those waters remain high seas.
  • EEZ Access Pass vs high-seas LoA: the Access Pass is for fishing in the EEZ and is free through ReALCRaft. The Letter of Authorisation is for the High Seas.

Mains Points

  • The open-access problem with shared fish stocks:
  • Tuna migrate across EEZs and the high seas, so one stock is shared by many fleets.
  • Under the IOTC yellowfin rebuilding plan, members whose 2014 catch was above 5,000 tonnes had to cut it by 21%. Yet total yellowfin catch in 2018 was about 9% above the 2014/15 level, because exempt countries and fleets that broke their limits caught more.

  • Lesson: freedom of fishing works only when it comes with the duty to conserve.

  • India's high-seas push needs to match its conservation duties (GS-III):

  • The Budget 2025-26 framework, the 2025 Guidelines and the LoA open the high seas to Indian boats.
  • From 2024, the IOTC encourages voluntary restraint, such as keeping tuna vessels out of the IOTC area for at least 31 days in a row.

  • India could adopt such measures and use catch reporting to defend its fair share of the stock and keep the trust of export buyers.

  • Governing the global commons:

  • The BBNJ Agreement fills a gap by adding high-seas marine protected areas, environmental impact assessments and benefit-sharing from marine genetic resources.
  • These tools are needed for 30x30 and SDG 14 (life below water).
  • They also need to be balanced against deep-sea mining interests, such as the ISA mining-code debate and India's Deep Ocean Mission.

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