Is India's internet boom running into an undersea problem?

One of India's biggest digital vulnerabilities sits on a six-kilometre stretch of Mumbai's Arabian Sea coast.

Around Versova, a densely populated neighbourhood on the city's northwest, at least 13 of India's 18 intercontinental submarine cables, external come ashore within six kilometres of one another.

Together they carry as much as 95% of India's international bandwidth to Europe, Africa and West Asia.

"This network faces a critical vulnerability due to severe geographic concentration," says Anwesha Sen of Takshashila Institution, a think tank.

"If several of those cables were cut simultaneously, either accidentally or deliberately, a bulk of India's westward bandwidth to West Asia, Africa and Europe would be impacted."

Cable architecture allows traffic to be rerouted, so a cut would not cause a total blackout.

Traffic could be diverted through other landing points, including the southern cities of Chennai and Kochi, say experts. (India's 18 subsea cables land in Mumbai, Chennai, Cochin, Tuticorin, and Trivandrum.)

But even performance degradation - small increases in the time it takes data to travel - could be costly for banks, stock exchanges, cloud providers and government networks. AI infrastructure may be particularly sensitive because it relies on high-volume, high-speed data transfers.

That vulnerability stems from how much of the world's digital traffic depends on these cables.

They are the internet's hidden highways - bundles of optical fibres on the ocean floor carrying data between continents as pulses of light. Humans have laid some 870,000 miles (1.4 million km) of them, "lacing the Earth tightly together", writes Samanth Subramanian in his new book The Web Beneath the Waves. These cables carry about 99% of global communication traffic.

Cheap data has helped make India one of the world's biggest internet markets. By late 2025, it had more than a billion broadband subscribers, external. India's growing digital economy and services sector increasingly depend on these cables.

But India's growing reliance on this invisible infrastructure sits uneasily with how little of it the country actually has.

India accounts for roughly 20% of global consumption of data, but is connected to only about 3% of the world's submarine cables.

It has 21 cable landing stations - coastal gateways where undersea cables connect to terrestrial networks - compared with roughly 1,900 planned and active globally, giving India about 1% of the world's total, according to the Broadband India Forum (BIF).

"We need to grow the number of cable landing stations several fold," says Aruna Sundararajan, chairperson of BIF.

Experts believe this is the paradox at the heart of India's digital transformation: the country is becoming an internet and data-centre powerhouse without controlling enough of the physical infrastructure that connects it to the world.

A recent paper by Takshashila Instituition finds that 11 of India's 18 international cables are more than 20 years old, approaching the nominal 25-year operating life of submarine cable systems.

"It's true that a significant share of India's landing cables are approaching economic end-of-life, and that is a legitimate area of focus," says Amajit Gupta, group CEO and managing director of Lightstorm, a digital infrastructure company.

And then there are cable faults - a far more common risk than deliberate attacks.

Globally, there are an estimated 150-200 cable faults a year, external, most caused not by saboteurs but by fishing, ship anchors, natural hazards and equipment failure.

"We've seen a version of this scenario play out with the Red Sea disruptions, external," Gupta said, when traffic was rerouted east through Singapore and onward to the US.

And when an undersea cable breaks, India has another striking weakness: it has no domestic subsea cable-repair ships.

Repair ships have to come from abroad and obtain permission to operate in Indian waters.

"Every cable fault in Indian waters depends on foreign repair ships from Dubai or Singapore. Once a foreign ship is assigned, it must obtain licences to operate in Indian waters, adding weeks to an already lengthy process," says Sen.

That dependence on foreign repair capacity is the more fundamental weakness.

"The bigger structural issue for India isn't rerouting capability - it's repair capacity," says Gupta.

"That combination – dependence on foreign repair capacity and regulatory lead times – represents the real bottleneck," he says.