In a landmark development, Indian scientists have captured the first-ever image of an active hydrothermal vent at a staggering depth of 4,500 metres in the Indian Ocean. This breakthrough, achieved under the ambitious Rs 4,000-crore Deep Ocean Mission spearheaded by the Ministry of Earth Sciences, marks a significant step in the country’s marine exploration efforts. The imaging effort is a culmination of over a decade of sustained exploration conducted by the National Centre for Polar and Ocean Research (NCPOR), along with the National Institute of Ocean Technology (NIOT).
Since 2012, NCPOR has been conducting geophysical surveys across the Central and Southern Ridges of the Indian Ocean in search of hydrothermal vents. These explorations have involved meticulous detection of water column anomalies and temperature variations, indicating that there is a potential hydrothermal activity beneath the ocean floor.
Hydrothermal Vents
Hydrothermal vents are essentially underwater hot springs that typically form in tectonically active regions. These vents arise when cold seawater, usually about two degrees Celsius, seeps into the oceanic crust through cracks and fissures. As the water interacts with magma from beneath the Earth’s crust, it gets superheated, reaching temperatures as high as 370 °Celsius or higher, and reemerges through the seafloor, carrying with it a host of dissolved minerals and gases.
The expelled fluids, rich in metals and other compounds, form distinctive chimney-like structures on the ocean floor. These structures, sometimes called ‘black smokers’, are not only mineral-rich but also host to unique ecosystems supported by microbial life, which thrives in the absence of sunlight through a process called chemosynthesis. Chemosynthesis allows organisms to convert inorganic molecules into energy using chemicals.
Targeting the Central Indian Ridge
Earlier in April 2024, the NCPOR team, aided by an autonomous underwater vehicle (AUV), pinpointed a specific site along the Central Indian Ridge as a probable location for hydrothermal activity. This led to a collaborative expedition between NCPOR and NIOT. The team was led by senior scientists John Kurian and N.R. Ramesh. The teams focused on conducting high-resolution deep-sea imaging of hydrothermal sulphide fields located along the Central and Southwest Indian Ridges in the Southern Indian Ocean.
A Breakthrough at 4,500 Metres
In December 2024, the joint expedition aboard the research vessel ‘Sagar Nidhi’ achieved a historic milestone. For the first time, an Indian AUV successfully captured detailed images of an active hydrothermal vent situated 4,500 metres below sea level. The AUV developed by NIOT and named Ocean Mineral Explorer 6000 (OMe 6000), navigated the extreme underwater terrain and gathered vital visual images and scientific samples. The observation lasted between 12 and 15 hours and offered high-resolution images into the vent chimney, black smokers, and signs of living chemosynthetic organisms. The successful deployment of OMe 6000 not only shows India’s advancements in deep-sea technology but further positions India among a select group of nations capable of conducting such high-stake underwater exploration.
According to NCPOR’s senior scientist, John Kurian, these vents could remain active for periods ranging from a few hundred years to as long as 30,000 years. This duration makes them not only valuable for scientific research but also significant from an economic perspective, considering the concentration of minerals such as copper, zinc, gold, silver, platinum, iron, cobalt, and nickel.
Scientific and Economic Significance
The discovery offers dual benefits. First, it has substantial economic implications due to the mineral-rich deposits formed by hydrothermal venting. These include rare earth metals and other elements vital for modern technologies and clean energy solutions. Second, from a scientific standpoint, it enables researchers to study the unique life forms that thrive in such extreme environments.
Unlike terrestrial life forms that rely on sunlight and photosynthesis, organisms around hydrothermal vents survive through chemosynthesis. Here, microbes utilise inorganic compounds like hydrogen sulphide to generate energy, sustaining the unique ecosystem. This process is considered a window into the possible origins of life on Earth, supporting biochemist Aleksandr (also spelt Alexander) Oparin’s chemosynthetic theory proposed in 1922, which suggested that initially, life could have originated on Earth through a series of combinations of chemical substances in the distant past and it all happened in water.
Visual Confirmation Validates Earlier Surveys
Dr Thamban Meloth, Director of NCPOR, stated that this achievement validates years of prior near-bottom surveys and geophysical studies, which had suggested the presence of hydrothermal activity in the region. The imaging offers definitive visual confirmation transforming what was once theoretical data into factual evidence.
Meloth emphasised that this breakthrough significantly boosts the confidence of the scientists in India’s Deep Ocean Mission. This mission’s broader objectives include mineral exploration, the study of deep-sea biodiversity and understanding the ocean’s role in climate regulation. The discovery has, therefore, come as a key success story in achieving these goals.
Overcoming Oceanic Challenges
Conducting such an expedition in the Southern Indian Ocean is a very difficult task. The region presents several operational challenges, including extreme depths, unpredictable ocean currents, and frequent stormy weather. The depth of the target site, ranging between 3,000 to 5,000 metres, along with complete darkness, makes such missions highly complex. During a typical one-month survey window, the researchers may only get one or two weeks of favourable weather for deploying the AUV and conducting observations.
Additionally, hydrothermal vents are very difficult to find as they are only one or two metres wide. Furthermore, they are scattered across vast oceanic regions making their detection comparable to ‘searching for a needle in hundreds of haystacks’. This underscores the critical role played by precise instrumentation and experienced personnel along with an element of luck in achieving success.
Autonomous Underwater Vehicle
A major highlight of this mission is the successful use of the OMe 6000, a self-programmed robotic AUV designed by NIOT. The vehicle was instrumental in smoothly navigating the rugged ocean floor and capturing the high-definition visuals of the hydrothermal vent. According to NIOT director, Balaji Ramakrishnan, this was the result of four expeditions conducted over the past two years, aimed at refining the search strategy and enhancing technological readiness.
He confirmed that although the initial imaging and data collection phase was successful, scientists are still in the process of analysing videos, photographs, and chemical samples gathered during the mission. These analyses are expected to yield deeper insights into both the geological and biological characteristics of the discovered site.
Future Directions and Broader Impacts
Following this milestone, NCPOR plans to proceed with TV-guided grab sampling, a technique that would allow precise retrieval of samples from the ocean floor. These samples would offer a better understanding of the surrounding features and economic viability of the mineral deposits.
This discovery is further expected to influence India’s future expeditions, including the upcoming ‘Samudrayaan’ mission, which aims to send human explorers to a depth of about 6,000 metres. The technological and scientific lessons, learnt from the hydrothermal vent imaging, would be foundational in planning and executing this next frontier in deep-sea exploration.
As part of this long-term strategy, India is also developing a new ship tailored for deep-sea surveys. Expected to be operational within three years, this vessel would further strengthen India’s capabilities in ocean exploration and contribute to a broader understanding of oceanic resources, ecosystems, and their role in global climate systems.
Contribution to the Global Scientific Community
The discovery aligns India with a select group of nations capable of conducting such high-stake underwater exploration. It highlights the country’s growing technological expertise and commitment to understanding one of the least explored frontiers on Earth. Moreover, it promises to contribute to international discussion around marine resource management and biodiversity conservation.
By venturing into the depths of the Southern Indian Ocean, Indian scientists are uncovering valuable resources of Earth sciences. As Meloth noted, “This is just the beginning”, sustained support, continued in the blue economy and persistent exploration efforts would be essential for India to unlock the vast, mysterious expanse of its deep ocean territory.
© Spectrum Books Pvt Ltd.
