When you video call someone in another country, you probably think your data travels through satellites.
It doesn't.
99% of international internet traffic travels through cables on the ocean floor.
Right now, there are over 400 submarine cables lying across the seabed, connecting continents. They're thinner than a garden hose but carry entire countries' internet traffic.
Let's explore the hidden infrastructure that makes the internet global.
The Surprising Truth About Internet Cables
Satellites Are Backup, Not Primary
Satellites handle:
- Remote areas (ships, planes, rural locations)
- Emergency backup
- About 1% of internet traffic
Why not satellites?
- Slow (signal travels 22,000 miles to space and back)
- Expensive
- Limited bandwidth
- High latency (delay)
Submarine cables:
- Fast (light through glass fiber)
- Cheap (once installed)
- Massive bandwidth
- Low latency
The Fiber Optic Miracle
Underwater cables are fiber optic cables.
How they work:
- Hair-thin glass fibers
- Light pulses represent data (on/off = 1/0 in binary)
- Light travels through fiber at 200,000 km/second
One fiber can carry:
- Terabits per second
- Equivalent to millions of HD video streams
A cable contains multiple fibers, multiplying capacity.
What These Cables Look Like
The Cross-Section
From inside out:
- Core: Glass fiber (carries light/data)
- Cladding: Another glass layer (keeps light inside)
- Coating: Plastic protection
- Strength members: Steel or Kevlar (prevents stretching)
- Copper tube: Power for signal amplifiers
- Waterproofing: Petroleum jelly
- Outer sheath: Polyethylene (plastic protection)
- Armor: Steel wires (protection near shore)
Near shore:
- Thick as your arm (heavily armored)
- Protected against ship anchors, fishing nets, sharks
Deep ocean:
- Thin as a garden hose (less armor needed)
- Lies on the seabed, sometimes buried
Fun fact: Despite their importance, most submarine cables are barely thicker than your thumb in deep water.
How They're Installed
The Cable-Laying Ship
Specialized ships install submarine cables:
Equipment:
- Giant spools holding thousands of kilometers of cable
- Plow (buries cable near shore)
- Remotely operated vehicles (ROVs) for repairs
- Precision GPS positioning
The process:
- Planning: Survey ocean floor, avoid volcanoes, fault lines, shipping lanes
- Manufacturing: Cable made to exact length (no joins possible once submerged)
- Loading: Coiled onto ship (takes days)
- Laying: Ship moves slowly (6-10 km/hour), paying out cable
- Burial: Near shore, cable buried 1-3 meters deep (protection)
- Deep ocean: Cable lies on seabed (too deep to bury)
Installation time:
- Transatlantic cable (6,000 km): 2-3 months
Cost:
- $200-$300 million per cable
Landing Stations
Where cables meet land:
What happens:
- Cable emerges from ocean
- Connects to "landing station" (building on shore)
- Converts optical signals to electrical
- Connects to terrestrial internet infrastructure
Security:
- High security (fences, cameras, guards)
- Backup power
- Redundant systems
These are critical infrastructure. Damage here could cut a country's internet.
The Route Map
Major Cable Systems
Transatlantic:
- Over 20 cables connecting North America to Europe
- Most traffic between US and EU
- First cable: 1858 (telegraph), modern fiber: 1988
Transpacific:
- Connect North America to Asia
- Massive capacity (US-China internet traffic)
- Growing fastest (Asia's internet boom)
Europe-Asia:
- Through Mediterranean, Red Sea, Indian Ocean
- Connect Europe to Middle East and Asia
- Alternative: Through Russia overland (political risks)
Inter-Asia:
- Connect Japan, South Korea, Taiwan, Southeast Asia, Australia
- Highest density of cables globally
Africa:
- Cables along coasts
- Connecting Africa to Europe and Asia
- Interior Africa still relies on slower satellite
The Chokepoints
Certain narrow waterways handle massive traffic:
Strait of Malacca (Singapore):
- Connects Indian Ocean to Pacific
- Dozens of cables pass through
- Singapore is a major internet hub
Suez Canal (Egypt):
- Cables connect Europe to Asia
- 2008: Ship anchor severed cables, cut 75% of Egypt's internet
Bosphorus (Turkey):
- Connects Europe to Asia
- Critical for Middle East connectivity
Damage to chokepoints can affect entire regions.
How Fast Is It?
The Speed of Light
Data travels through fiber at about 200,000 km/second (2/3 the speed of light in vacuum).
Real-world examples:
New York to London:
- Distance: 5,500 km
- Cable route: ~6,000 km (not straight)
- Travel time: 30 milliseconds (0.03 seconds)
San Francisco to Tokyo:
- Distance: 8,000 km
- Cable route: ~9,000 km
- Travel time: 45 milliseconds
Sydney to Los Angeles:
- Distance: 12,000 km
- Cable route: ~13,000 km
- Travel time: 65 milliseconds
That's faster than you can blink (100-150 milliseconds).
Why Gamers Care About Latency
Online gamers obsess over "ping" (round-trip time).
Example:
- You (Bangkok) play game server (Singapore)
- Cable: ~1,500 km
- Ping: 10-15 milliseconds (great)
But:
- You (Bangkok) play server (Europe)
- Cable: ~15,000 km
- Ping: 150-200 milliseconds (laggy)
Physics limits speed. Can't beat the speed of light.
This is why:
- Games have regional servers
- Stock trading happens near exchanges (every millisecond matters)
- Content Delivery Networks (CDNs) cache data closer to users
What Can Go Wrong
Shark Attacks (Yes, Really)
Sharks bite submarine cables.
Why?
- Electromagnetic fields from power cables attract sharks
- Curiosity
- They bite everything
Solution: Modern cables have shark-resistant coatings.
Fun fact: Google protects cables with Kevlar wrapping specifically because of shark bites.
Ship Anchors
The #1 cause of cable damage:
How it happens:
- Ship drops anchor
- Anchor drags along seabed
- Snags cable
- Cable breaks
Prevention:
- Bury cables near shore
- Mark cable locations on nautical maps
- Fine ships that damage cables
When it breaks:
- Repair ship dispatched
- Locates break (using signal testing)
- Retrieves both ends
- Splices in new section
- Repair time: Days to weeks
Earthquakes
Underwater earthquakes can sever cables.
2006 Taiwan earthquake:
- Magnitude 7.0
- Severed 9 cables
- Internet in China, Taiwan, Hong Kong, Singapore disrupted for weeks
- Estimated economic damage: $100+ million
2011 Japan earthquake:
- Tsunami damaged cables
- Japan's internet partially cut
- Repairs took months
Sabotage
Cables are vulnerable to intentional cutting.
2013: Divers cut fiber cables near Alexandria, Egypt (motive unclear)
Russia-Ukraine conflict: Concerns about deliberate cable sabotage
National security worry: Enemy nations could cut cables during conflict, isolating countries.
Response: Navies monitor critical cables, have repair ships ready.
Who Owns These Cables?
The Players
Tech giants:
- Google: Owns/part-owns 15+ cables
- Facebook (Meta): Owns several, planning more
- Amazon: Investing in cable infrastructure
- Microsoft: Part-owner of multiple cables
Why? They generate massive traffic (YouTube, Facebook, AWS, etc.). Cheaper to own infrastructure.
Telecom companies:
- AT&T, Verizon, Orange, BT, etc.
- Traditional cable owners
- Sell capacity to others
Cable consortiums:
- Groups of companies share costs
- Each gets portion of capacity
Example: "Southeast Asia-Middle East-Western Europe 5 (SEA-ME-WE 5)" cable is owned by 20 telecom companies across multiple countries.
The Economics
Building a cable:
- Cost: $200-$500 million
- Lifespan: 25 years
- Capacity: Terabits per second
Selling capacity:
- Companies "lease" bandwidth
- Price: Varies, but profitable over cable's lifetime
Why it's worth it: A single cable can carry a country's entire internet traffic.
How Redundancy Works
Multiple Cables
No single cable is critical.
Example: US to Europe:
- 20+ cables
- If one breaks, traffic reroutes through others
- Users rarely notice
Small countries are vulnerable:
- Tonga: 1 cable (cut by volcano in 2022, island offline for weeks)
- Pacific islands: Often 1-2 cables (limited redundancy)
Rerouting Traffic
Internet protocols automatically reroute:
- Cable breaks
- Routers detect failure
- Traffic rerouted through alternate cables
- Users experience slower speeds (more traffic on fewer cables)
- Normal service resumes when repaired
This happens invisibly, constantly.
The Future of Submarine Cables
More Cables
Trends:
- 50+ new cables planned for next 5 years
- Higher capacity (400 Terabits/second per cable)
- Connecting underserved regions (Africa, Pacific Islands)
Tech Giants Dominate
Google, Facebook, Amazon building their own cables:
- Control infrastructure
- Avoid paying telecom companies
- Ensure capacity for their services
Google's cables:
- Dunant (US-France)
- Grace Hopper (US-UK)
- Curie (US-Chile)
First time private companies, not telecoms, dominate submarine cable installation.
New Routes
Arctic cables:
- Climate change melting Arctic ice
- Shorter routes: Europe to Asia over the top
- Controversial (environmental, geopolitical)
Space-based internet:
- Starlink, OneWeb (satellite constellations)
- Not replacing cables (capacity/cost)
- Serving remote areas cables can't reach
Why This Matters
The Internet Isn't "In the Cloud"
The cloud is actually:
- Data centers (buildings full of servers)
- Connected by cables (under oceans)
There's no wireless magic. Everything connects physically.
Geopolitical Implications
Countries that control cables have power:
- Can monitor traffic
- Can cut access
- Strategic national security concern
US concern: China building cables globally. Could China intercept data?
Chinese concern: US/allies control many cables. Could they cut China off?
Economic Dependence
Modern economy requires internet:
- Banks
- Stock markets
- Cloud services
- Remote work
Cable damage = economic disruption.
2008 cable cuts (Mediterranean):
- Egypt, India, UAE, Pakistan affected
- Banking disrupted
- Call centers couldn't operate
- Estimated losses: Billions
The Bottom Line
When you stream Netflix, video call family overseas, or load a foreign website:
Your data travels through:
- Cables under the ocean floor
- Thinner than your arm
- Lying at depths of 8,000 meters
- Carrying light pulses at 200,000 km/second
The internet isn't wireless. It's wired.
Satellites are backup. The real work happens through cables.
Over 400 cables, 1.4 million kilometers total length, connecting every continent.
That's how the global internet actually works.
Next time you load a webpage from another continent in under a second, remember: your request just traveled thousands of kilometers through a cable on the ocean floor.
⚠️ DISCLAIMER
Educational Content Only: This article explains submarine cable infrastructure for informational purposes. Cable routes, ownership, and technical specifications change as new cables are installed. The author is not a telecommunications engineer or network infrastructure specialist. This simplified explanation makes technical concepts accessible. For technical implementation or infrastructure planning, consult qualified telecommunications professionals and official cable documentation. Security and geopolitical assessments are simplified for general understanding. Maximum liability: $0.
References
- TeleGeography. (2024). "Submarine Cable Map." Interactive Database.
- International Cable Protection Committee (ICPC). (2024). "Cable Protection Guidelines." Industry Standards.
- Google Cloud. (2024). "Submarine Cable Investments." Corporate Documentation.
- IEEE. (2024). "Submarine Fiber Optic Communications." Technical Journal.
- Submarine Telecoms Forum. (2024). "Industry Report: Global Submarine Cable Market." Market Analysis.
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