When you stream a movie, join a video call, or upload a file to the cloud, chances are your data is traveling thousands of miles through the ocean floor. Despite all the hype about satellites and 5G, subsea cables remain the backbone of the global internet, carrying more than 95% of international data traffic.
In 2025, these hidden lifelines are expanding rapidly, driven by the demands of cloud providers, AI workloads, and global connectivity. Understanding their role is key to appreciating how digital infrastructure truly works.
Why Subsea Cables Are Essential
- Data Volume: Subsea fiber cables transmit vast amounts of data far more efficiently than satellites.
- Low Latency: Ocean-floor cables enable millisecond-level communication, crucial for financial trading, AI, and real-time applications.
- Capacity Growth: With AI-driven demand exploding, new high-capacity cables are being laid across the Atlantic, Pacific, and Arctic routes.
- Global Reach: Subsea cables connect continents, enabling cloud services and global digital trade.
Subsea Cables vs Satellites
While satellite internet is often portrayed as a challenger, the reality is more nuanced:
| Feature | Subsea Cables | Satellites (LEO/MEO/GEO) |
|---|---|---|
| Data Capacity | Extremely high, terabits per second | Lower capacity, shared bandwidth |
| Latency | Very low (milliseconds) | Higher (20–50ms for LEO, 500ms+ for GEO) |
| Reliability | Stable, less affected by weather | Can be disrupted by storms, solar events |
| Cost per Unit Data | Lower at scale | Higher, especially for high usage |
| Best Use Cases | Global internet backbone, cloud, AI | Rural access, emergency connectivity, redundancy |
Conclusion: Satellites complement subsea cables but cannot replace them. The two work together, with cables handling heavy lifting.
Major Projects in 2025
Several high-profile projects are redefining internet connectivity:
- Google’s “Equiano” Cable: Connecting Europe to Africa, expanding capacity for emerging markets.
- Meta & Partners’ “2Africa” Cable: One of the longest ever, encircling the African continent.
- Pacific Connect Initiatives: Expanding U.S.–Asia connectivity, crucial for trade and AI workloads.
- Arctic Routes: New experimental projects aim to shorten data routes between Europe and Asia via the Arctic, enabled by melting ice.
These cables are often funded not just by telecom operators but increasingly by hyperscale cloud providers like Google, Microsoft, and Meta, who want to control their own data pathways.
Challenges Facing Subsea Infrastructure
- Physical Damage: Cables can be cut by ship anchors, earthquakes, or fishing activity.
- Geopolitics: Control over cables is becoming a national security issue, with countries vying for influence.
- Environmental Concerns: Though less impactful than other marine activity, laying cables still raises ecological questions.
- Maintenance Costs: Repair ships and teams are expensive, and downtime can disrupt regional connectivity.
Frequently Asked Questions (FAQ)
How many subsea cables exist worldwide?
As of 2025, there are over 500 active subsea cables spanning more than 1.5 million kilometers.
Do satellites threaten subsea cables?
No. Satellites are valuable for rural access and redundancy but cannot match cables in capacity or cost efficiency.
How long does it take to build a subsea cable?
Planning, permits, and construction can take 2–4 years, depending on length and complexity.
Who owns subsea cables?
Ownership is often shared by consortia of telecoms, cloud providers, and governments. Increasingly, hyperscalers like Google and Meta finance their own.
What happens if a cable is cut?
Traffic is rerouted to other cables, but this can cause congestion and slower speeds. Repairs typically take days to weeks.
Key Takeaway
Subsea cables are the invisible foundation of the internet. While satellites, 5G, and other innovations grab headlines, it’s these fiber-optic arteries under the ocean that keep the digital economy running.
In 2025 and beyond, the expansion of subsea infrastructure will shape how fast, secure, and equitable global connectivity can be. Without them, the cloud, AI, and the connected future would grind to a halt.