1) What are undersea cables

Undersea (subsea) cables are long fibre-optic cables laid on the seabed that carry internet and phone data between countries. Think of them as the international highways of the internet. Inside each cable are hair-thin glass fibres that move data as light; outside are many protective layers for strength and waterproofing. Special cable-laying and repair ships install and fix them across oceans.

Key facts

• Carry well over 95% of global, intercontinental data traffic (much more than satellites)

• Stretch thousands of kilometres, linking landing stations on different coasts

• Use repeaters every few dozen kilometres to keep the optical signal strong

2) Why they matter so much

Almost everything we do online depends on these cables. Because fibre has very low delay and very high capacity, it keeps our digital life smooth.

Why this matters

• Powers payments, stock trading, cloud services, video calls, streaming, gaming, and cross-border company networks

• Critical for e-governance, tele-health, and online education

• Important for national security and international coordination

• When a big cable (or two) goes down, traffic is rerouted but slows: users see laggy apps, buffering video, and slow file transfers

Recent concern

• In the last two years, multiple cuts on busy routes (for example, the Red Sea–Suez corridor) led to latency spikes and region-wide slowdowns across India, the Gulf, and South-East Asia until repairs finished

Underseas Internet cables

3) What breaks them

Cables are tough, but faults still happen—mostly near coasts.

Common risks

• Anchors and fishing gear dragging on the seabed (top cause in shallow waters)

• Earthquakes, seabed landslides, and volcanic activity in deep ocean

• Accidental construction damage near ports and harbours

• Deliberate cuts or sabotage in conflict zones (rare but serious)

• Espionage attempts are uncommon and technically difficult, but a security worry

How an outage unfolds

• Traffic shifts to other cables, causing congestion and slower service

• Repair ships must mobilise with spare cable and repeaters; weather and permits can delay work, so fixes may take days to weeks

4) India’s risk profile

India’s digital economy is large and growing fast, so we are more exposed when big routes choke.

What to watch

• Landing concentration: many major systems land around Mumbai (west coast) and Chennai (east coast); a cluster hit can affect a large share of traffic

• Route chokepoints: global cables pass through narrow corridors like Red Sea–Suez and the Strait of Malacca; disruptions there ripple into India–Europe and India–Asia paths

• Repair logistics: deep-sea work needs special ships; nearby depots are limited, and approvals plus weather add time

• Security angle: landing stations and near-shore segments need strong physical and cyber security to deter sabotage or interference

• Economic impact: slower cross-border connectivity hurts information technology services, startups, financial technology, business process outsourcing, exports, and even routine international payments

5) How to reduce the risk

No one can make risk zero, but we can limit damage and recover faster.

Technical and operational

• Route diversity by design: buy capacity on multiple cable systems using different paths (west via Middle East/Europe; east via Singapore/Pacific)

• More landing stations, better spread: add or upgrade landings beyond the two mega hubs to cut single-cluster risk

• Protect near-shore segments: mark no-anchoring and no-trawling zones on nautical charts; conduct awareness drives for ships and fishers

• Rapid repair readiness: pre-contract repair ships, stock spare cable and repeaters, fast-track permits; run multi-agency drills with telecom operators, navy, coast guard, and port authorities

• Harden landing facilities and localise traffic: redundant power and fibre, strict access control, and more content caching and peering inside India to soften external cuts

Policy and diplomacy

• Publish a national subsea-resilience plan with standards, audits, and incident reporting

• Build regional agreements for protection and fast repair corridors through chokepoints; encourage domestic capability in cable manufacture, maintenance, and skilled crews

6) Bottom line for exams

Undersea cables are the backbone of the global internet and of India’s digital economy. Since most international data runs on fibre under the sea, cable cuts can slow economies and disrupt services. India must build route diversity, more landing points, better protection near coasts, faster repair systems, and strong security at landing stations. This is both a telecom resilience and a national-security issue.

Mains Practice (150–200 words)

Question: “Damage to undersea cables is both an economic and national-security risk for India.” Explain with recent examples and suggest immediate and long-term measures.
Hints to use: mention recent multi-cable cuts on busy routes causing latency spikes; explain India’s landing concentration (Mumbai/Chennai), route chokepoints (Red Sea–Suez, Malacca), and repair delays. Immediate steps: failover routing, traffic balancing, no-anchor zones, pre-contracted repair ships, landing-station hardening. Long term: more landing diversity, new east and west systems, local caching and peering, regional agreements for fast repairs, and a national resilience plan.

Prelims Practice (MCQ)
Question: Consider the following statements about undersea cable resilience:

1. Most intercontinental data travels via subsea fibre, not satellites.

2. The majority of cable faults occur in deep ocean rather than coastal waters.

3. India’s cable landings are concentrated around Mumbai and Chennai.

4. Repairing a subsea cable typically needs specialised ships and permits, so fixes can take weeks.
   Which of the statements given above are correct?
   A. 1, 3 and 4 only
   B. 1 and 2 only
   C. 2 and 4 only
   D. 1, 2, 3 and 4
   Answer: A (1, 3 and 4 only)
   Why: (1) True. (2) False—most faults are in shallow waters due to anchors and fishing. (3) True. (4) True—repairs need ships, permits, and fair weather.

One-line wrap: Protect the pipes of the internet—diverse routes, secure landings, and quick repairs keep India online when seas get rough.