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India last week signed a contract with the International Seabed Authority (ISA) for exclusive rights to explore Polymetallic Sulphides (PMS) in the Carlsberg Ridge in the Indian Ocean.
With this, India has become the first country in the world to have two contracts with the ISA for PMS exploration. It now commands the largest area allocated in the international seabed for PMS exploration — a scientific achievement with strategic importance.
Goa-based National Centre for Polar and Ocean Research (NCPOR) will carry out the PMS exploration in 2026, starting with geophysical and hydrographic surveys in the licensed area.
India had submitted an application to the ISA in 2024. Following the evaluation process, the ISA last week allotted India a 10,000 square km area in the Carlsberg Ridge.
The earlier contract is in the Central Indian Ridge and Southwest Indian Ridge, signed in 2016.
Polymetallic Sulphides are deposits on the ocean floor, rich in strategic and critical metals such as copper, zinc, lead, gold, and silver, along with trace amounts of rare and precious elements.
Since land resources containing these minerals are very limited for India, exploring PMS in the deep ocean could enhance resource security. These metals are essential for high-technology applications, renewable energy systems, and green technologies.
PMS deposits are generally found near hydrothermal vents, which are like hot springs on the ocean floor. The ocean seabed has cracks. Through these cracks, the cold seawater interacts with the magma under the earth’s crust, and is expelled back in a hot gush. This expelled water is rich in minerals, which are then deposited on the ocean floor as solids.
Since the signing of the contract with ISA in 2016, NCPOR has been conducting exploratory surveys along the central and southwest Indian Ocean ridges. The institute has thus developed expertise and built advanced infrastructure for PMS exploration.
The ongoing Deep Ocean Mission program of the government has enhanced these capabilities, including the acquisition of new deep-sea vessels and advanced tools, such as Autonomous Underwater Vehicles (AUVs). Matsya, a deep-sea vehicle under development for the ambitious Samudrayaan mission, will provide an additional boost to India’s deep-ocean mineral exploration capacity.
The NCPOR’s plan is three-phased:
Phase I: Conduct reconnaissance surveys using ship-mounted tools and identify potential locales of PMS
Phase II: Conduct near-seabed surveys using advanced tools such as AUVs and Remotely Operated Vehicles (ROV) to confirm the occurrence of PMS
Phase III: Resource-evaluation of the identified PMS deposits.
The Carlsberg Ridge is a major segment of the mid-ocean ridge system in the Indian Ocean, formed by seafloor spreading between the Indian Plate and the Somali Plate. It is estimated that the current phase of opening of the Carlsberg Ridge began at about 40 million years ago following a major plate reorganisation and its average spreading rate is of 2.4 to 3.3 cm/year. The ridge has a rough flanking topography and a median valley, which are the characteristics of slow-spreading ridges.
The ridge is known to host hydrothermal vent systems, potential sites of PMS deposits. India has conducted scientific research on these systems during the past three decades. Strategically, the Carlsberg Ridge is particularly important because it is located much closer to India (around 2 degree north) compared with the Central and Southwest Indian Ridges (around 26 degree south).
Exploration for PMS is technically more challenging than other deep-sea mineral investigations. PMS deposits are concentrated near hydrothermal vent systems along mid-ocean ridges, where the seabed is composed of hard, highly complex and uneven rocky terrain at depths of 2,000–5,000 meters. They are generally located in some of the remotest areas of the planet.
PMS survey operations are thus challenging, requiring deep-sea vessels with dynamic positioning and precise navigation and communication systems.
PMS exploration demands a highly multidisciplinary team with expertise in marine geology, geophysics, oceanography, biology and deep-sea technology. Exploration tools include ship-mounted geophysical and hydrographic survey systems for reconnaissance, and AUVs and ROVs for near-seabed surveys and sample collection. Advanced sampling tools and analytical instruments are needed to characterise mineral composition accurately.
The ISA is an autonomous international organisation. It allocates sites for mineral exploration in international waters under the United Nations Convention on the Law of the Sea (UNCLOS) framework. A country, either through its government, public sector, or sponsored entity, can submit applications to the ISA.
This application must identify a proposed exploration area along with a detailed work plan, environmental baseline studies, and financial/technical capability documents. The ISA’s Legal and Technical Commission (LTC) is responsible for reviewing the application for compliance, and if it meets all requirements, recommends it to the ISA Council for the final approval.
India is looking to acquire additional sites in the Indian Ocean for mineral exploration as part of the Blue Economy initiatives of the Government of India. Specifically, India is interested in the exploration of cobalt-rich ferromanganese crusts on the Afanasy-Nikitin Seamount in the Central Indian Ocean. This application is under review.
