India’s deep dive into the frozen frontier

When Russian research vessel MV Vasily Golovnin sliced through the frigid waters of the Southern Ocean last December, few could have imagined the quiet breakthrough unfolding beneath the waves.

Onboard, Indian scientists Suresh Kumar from the Indian National Centre for Ocean Information Services (INCOIS) and Jenson from the National Centre for Polar and Ocean Research (NCPOR), Goa, were preparing to deploy an autonomous ocean glider — a sleek, torpedo-shaped instrument designed to skim through the ocean depths without a propeller, powered only by buoyancy shifts.

The expedition commenced from Cape Town in South Africa en route to Indian Antarctica second station ‘Bharati’, during which the glider was successfully deployed as part of the 44th Indian Scientific Expedition to Antarctica (ISEA). Over the next 61 days, from February 3 to April 7 last year, the glider travelled 1,300 km through some of the harshest marine conditions on the planet, collecting data on temperature, salinity, oxygen levels and chlorophyll.

Battling severe sea conditions, the Indian scientists team later retrieved the glider without any damage to the instrument, during the return voyage from the first Indian Antarctica station ‘Maitri’ to Cape Town “demonstrating the reliability and robustness of autonomous glider operations under extreme polar conditions”.

“These gliders allow us to collect high-resolution data continuously, even in remote and hostile environments. This achievement underscores India’s growing leadership in autonomous ocean observations and lays a strong foundation for future long-duration glider missions,” says Hyderabad-based INCOIS group director (Ocean Observations) E. Pattabhi Rama Rao.

The Southern Ocean, encircling Antarctica, is one of Earth’s most critical climate regulators. Its swirling currents and icy waters influence global weather patterns, carbon cycles and sea-level rise. At the heart of this dynamic system lies the ‘Polar Front’, a boundary where cold Antarctic waters meet warmer Sub-Antarctic waters, driving powerful air-sea exchanges.

“Understanding this region is vital for predicting climate change impacts. Our glider mission is a step towards filling critical gaps in ocean observations,” says INCOIS director T.M. Balakrishnan Nair.

Unlike conventional research vessels or powered drones, ocean gliders do not rely on propulsion systems but move by altering their buoyancy, allowing them to glide gracefully through the water column. This energy-efficient design enables missions lasting several months, covering thousands of kilometres, say scientists.

So far, INCOIS has successfully executed around 10 autonomous deep-sea glider deployments — eight in the Bay of Bengal and two in the Arabian Sea — as part of the ‘Deep Ocean Mission’. These deployments aim to explore and monitor oceanographic parameters using buoyancy-driven movement. The latest success in Antarctic waters adds polar capability to India’s expanding ocean observation programme.

The Slocum G-3 gliders, sourced from the United States of America, can manoeuvre both vertically and horizontally at speeds of about 8 to 10 centimetres per second, enabling extended missions lasting several months. They can travel up to 20-25 kilometres per day, dive to depths of 1,000 metres, and are tracked by satellites. They are remotely operated and monitored round the clock from the command centre of the institute here in Pragatinagar.

The gliders surface every five to six hours during 1,000-metre dive missions to transmit data while continuously measuring key ocean parameters using advanced biogeochemical sensors. While basic data is transmitted in almost real time when the gliders surface multiple times a day, the detailed datasets are retrieved when the system ”having an approximate lifespan of eight to nine months” is recovered from the water, scientists explain.

Before deployment, the gliders are configured and ballasted at the National Glider Test Facility established at INCOIS and subsequently tested through sea trials in shallow coastal waters. Data collected from these gliders, combined with observations from other monitoring systems such as tide gauges, argo floats and buoys, significantly enhances understanding of climate change impact on sea level, cyclonic storms, waves, swell surges and marine ecosystems, explains Mr. Nair.

Buoyed by this success, INCOIS is now planning an audacious mission: to deploy a next-generation ocean glider with enhanced battery endurance to undertake an unprecedented long-distance transect ”from near-shore Antarctica, close to Bharati station, to the coast of Gujarat covering an estimated distance of approximately 9,800 km”.

It would represent a first-of-its-kind long-distance mission, not only for India but globally ”a meridional transect conducted entirely by an autonomous ocean glider”. The mission is expected to advance scientific understanding of air-sea interactions across hemispheres. It will stand as a landmark endeavour and a matter of national pride, adds Mr. Nair.

Published – January 02, 2026 11:46 pm IST