Submarine Cables: What Are They and How Do They Work?

Submarine cables are the lifelines of modern communication. Stretching across the ocean floors, they carry over 95% of international data traffic and support industries worldwide. Submarine cables are one of the most remarkable yet hidden technologies that underpin our connected world and run our global economy.

In this article, I’ll explore what submarine fiber optic cables are, how they function, and why they are so essential to various industries. 

Key Takeaways

• Fiber optic submarine cables are underwater cables laid across ocean floors to transmit data or electricity over long distances, linking countries and continents.
• These cables, made up of multiple layers to protect the delicate optical fibers within, facilitate high-speed data transfer through light signals.
• A submarine cable network is installed by specialized vessels and maintained by cable ships to ensure reliable connectivity.
• The International Cable Protection Committee (ICPC) and the International Telecommunication Union (ITU) are among the leading organizations governing submarine cable network installation and operation.
• Regulations ensure operational security, data integrity, and environmental protection, which are essential for maintaining the stability of this critical infrastructure.

What Are Submarine Cables?

Submarine cables, also called undersea cables, sea cables, or underwater cables, are long, durable cables laid across the seabed. These cables can transmit data and electricity between continents and countries. Since these cables are critical to connectivity, their installation requires precise engineering and extensive planning to withstand ocean conditions for decades.

Anatomy of a Submarine Cables

The construction of undersea fiber optic cables is designed to protect its core components while withstanding extreme pressures and hazards on the ocean floor. Here’s a look at its primary layers:

• Conductor: The heart of the cable, typically made of copper or aluminum, carries the electrical current or data signals.
• Optical Fibers: In communication cables, this core houses a bundle of tiny glass fibers that transmit data using pulses of light.
• Insulation and Shielding: Surrounding the conductor or optical fibers, layers of insulating materials like polyethylene and petrolatum protect the core from water and other environmental factors.
• Steel Wire Armor: A robust layer of steel wires provides mechanical protection to the cable, shielding it from potential damage caused by external forces such as fishing nets or ship anchors.
• Outer Sheath: The outermost layer, often made of polyethylene, acts as a waterproof and abrasion-resistant barrier, safeguarding the cable from the harsh marine environment.

Submarine Cable Owners

Undersea cables are often owned by telecommunications companies, governments, and international consortiums. Tech giants like Google, Microsoft, and Facebook have also invested in these systems to ensure reliable data transmission for their global services. Additionally, some countries maintain ownership or share ownership of submarine cable systems for national security and economic reasons, reflecting the critical importance of this infrastructure.

Submarine Cable Applications

Submarine cables are an investment and critical infrastructure. Their primary applications include:

• High-Speed Internet: Multiple cable systems facilitate global internet connectivity, enabling fast and reliable data transfer for individuals and businesses worldwide.
• International Telecommunication: Powering international voice communication, from simple phone calls to complex telecommunications networks.
• Financial Transactions: Underpinning the global financial system by securely transmitting financial data between banks and institutions.
• Energy Transmission: Transporting electricity generated from offshore renewable energy sources, such as wind farms, to onshore power grids.
• Scientific Research: Supporting oceanographic research, climate monitoring, and other scientific endeavors by providing reliable communication links to remote locations.

How Does the Submarine Cable System Work?

To understand how seamless global communication is possible, we'll explore the installation and transmission processes behind the submarine cable network. 

Installation of a Submarine Cable System

1. Route Planning and Survey: Engineers carefully study marine charts, geological surveys, and historical data to identify the most suitable path across the ocean floor. They consider factors like water depth, seabed composition, and potential environmental impacts to minimize disruption to marine ecosystems.
2. Cable Manufacturing: Once the undersea cable routes are determined, cable companies build the cable itself. The manufacturing process involves precision and quality control to ensure the cable can withstand the immense pressures and harsh conditions of the deep sea.
3. Cable Loading and Mobilization: The newly manufactured undersea fiber optic cable is carefully loaded onto a specialized cable-laying vessel. The cable is coiled onto massive drums, ready to be unfurled onto the ocean floor.
4. Pre-lay Survey: Before the cable can be laid, a thorough survey of the seabed is conducted to identify any potential obstacles or hazards. This involves using advanced sonar and other underwater imaging techniques to map the ocean floor in detail. Any underwater debris, such as old cables or shipwrecks, must be identified and avoided to prevent damage to the new cable.
5. Cable Laying and Burial: The cable is gradually unfurled from the ship and sinks to the seabed. The ships that lay submarine cables avoid shallow waters. Here, the cable is protected from fishing nets, anchors, and other potential threats using a special plow that digs a trench in the seabed and lays the cable inside.
6. Shore-end Installation: The final step is to connect the undersea cables to the land-based telecommunications network. The cable must be securely anchored and protected from the forces of waves and tides. In some cases, the cable may be buried beneath the seabed to the shore, while in others, it may be supported by underwater structures.
7. Post-Lay Inspection and Burial (PLIB): The Post-Lay Inspection and Burial (PLIB) phase involves deploying a Remotely Operated Vehicle (ROV) to meticulously inspect the newly laid cable. The ROV, equipped with high-resolution cameras and specialized tools, examines the cable for any potential damage or irregularities that may have occurred during the laying process.

Data Transmission

Subsea cables use fiber-optic technology to transmit data at the speed of light. Lasers on one end fire at extremely rapid rates down thin glass fibers. The receptors at the other end of the cable receive the signals. Light signals encode data, enabling vast amounts of information to travel across thousands of miles in seconds.

Today, undersea cables can transmit data at speeds exceeding several terabits per second. The cable's capacity keeps pace with modern demands for high-speed internet and data transmission. Imagine a massive, high-speed underwater highway, connecting continents. 

That’s essentially what Google’s new 3900-mile Grace Hopper submarine cable is. This submarine cable, installed in 2021, is capable of transmitting data at 340-350 terabits per second in New York, London, and Spain. To put it into perspective, this single cable system could allow 17.5 million people to stream 4000 movies simultaneously without any lag or buffering. 

Power Source

Power feeding equipment provides a steady current to power undersea cables. This equipment can sustain long-term operations and allow an ultra-high voltage output to supply power for long-distance underwater cable systems. Since the power feeding equipment generates a high voltage from DC blocks, it is designed with electrical safety features such as keyed locks, auto shutoff, protection covers, and emergency stop buttons, to ensure a high level of safety.

Submarine Cable Landing Stations

Submarine cable landing systems are critical points where undersea cables transition from the ocean to land. A cable landing station connects vast underwater networks to terrestrial communication infrastructures. These systems are located at landing stations near coastlines.

They house specialized equipment that amplifies and distributes data signals, ensuring smooth, high-speed connectivity from the undersea infrastructure to inland networks. Different subsea cables are connected to associated landing stations. Cable landing systems are built with robust security measures and environmental protections to safeguard data integrity and support global internet infrastructure effectively.

Submarine Cable Map

The TeleGeography Cable Map 2024 records 559 cable systems and 1,636 landings that are currently active cables and planned cables. Additionally, almost 82% of the world's inter-regional bandwidth connects to the U.S. and Canada via fiber optic cables. Subsea cables span the world’s oceans, creating an undersea infrastructure that links continents and major economic hubs. 

Here’s a breakdown of where these cables are primarily located:

1. Atlantic Ocean: A dense concentration of undersea cables crosses the Atlantic, particularly between the eastern United States and Western Europe. This route is one of the oldest and most heavily used. Transatlantic cables support high-speed connections between tech and financial centers like New York, London, and Frankfurt.
2. Pacific Ocean: Several major cables run between North America, Asia, and Oceania, linking countries like the United States, Japan, South Korea, and Australia. These routes support communication and data flow across the world’s largest ocean, connecting significant tech and economic regions.
3. Indian Ocean: The Indian Ocean hosts key cables connecting Asia, the Middle East, and Africa. These cables play an important role in linking countries like India, the United Arab Emirates, and South Africa, enabling data transfer across emerging markets and global supply chain routes.
4. Regional Seas: Many cables are installed in regional seas such as the Mediterranean Sea, the North Sea, and the Caribbean Sea to support localized connectivity between nearby countries. For example, cables in the Mediterranean link Europe to North Africa and the Middle East, while cables in the North Sea connect the UK to mainland Europe.
5. Coastal Waters and Landing Stations: Undersea cables also extend into coastal waters where they connect to landing stations. Coastal landing stations point where cables come ashore and link to terrestrial networks. These landing stations are typically located near major cities or data hubs to facilitate high-speed data transmission inland.

Submarine cable hubs are strategic locations where multiple undersea cables converge, creating high-capacity data exchange points essential for global connectivity. These hubs are typically located in coastal cities with well-developed telecommunications infrastructure, such as New York, London, Singapore, and Tokyo.

Regulatory Oversight of Submarine Cables

Undersea fiber optic cables are governed by a complicated network of national and international legislation. These rules guarantee these infrastructure assets' dependability, safety, and security.

Key International Regulatory Bodies and Local Jurisdictions

Submarine cables are not only critical to global communications but also to national security and economic stability, making regulatory oversight essential. Various international organizations and local authorities work together to maintain the safe and sustainable operation of this infrastructure.

The International Cable Protection Committee (ICPC)

The International Cable Protection Committee (ICPC) protects and manages submarine cables worldwide. It provides guidance and recommendations to ensure the safe installation, operation, and maintenance of undersea cables. The ICPC works closely with governments, telecommunications companies, and environmental organizations to promote best practices and mitigate risks such as accidental cable damage from fishing, anchoring, or other maritime activities.

The International Telecommunication Union (ITU)

The International Telecommunication Union (ITU), a specialized agency of the United Nations, is responsible for coordinating the global standards for telecommunication and information technologies, including submarine cables. The ITU establishes technical standards, allocates frequencies, and ensures the seamless operation of global communication networks. Its work in regulating submarine cables includes fostering international cooperation to ensure the interoperability and security of these critical infrastructures.

Local Jurisdictions

National regulations may apply to cable landings and maintenance in territorial waters, ensuring adherence to local safety protocols and environmental standards. These organizations collaborate to set best practices for cable laying, maintenance, and protection and aim to reduce risks to marine life and underwater ecosystems. Coordinated regulation across jurisdictions helps prevent disruptions from human activities, natural events, and cable damage and preserves the global cable network’s integrity.

In the United States, submarine cable regulation falls under the jurisdiction of the Federal Communications Commission (FCC), a federal energy regulatory commission dedicated to managing telecommunications infrastructure. The FCC oversees the licensing of undersea fiber optic cables that land on U.S. shores, ensuring they comply with national security, environmental, and operational standards.

The FCC works in coordination with agencies such as the U.S. Department of State and the National Oceanic and Atmospheric Administration (NOAA). They enforce regulations that safeguard U.S. interests and environmental integrity relevant to submarine cable installation and operations. Meanwhile, they also ensure smooth data connectivity with international networks.

The FCC’s International Bureau, Telecommunications and Analysis Division (TAD) issues licenses to own and operate submarine cables and associated landing stations in the United States. Cable landing license applicants must meet the compliance requirements of submarine systems. This approach to regulation highlights the importance of national oversight in managing cable infrastructure within territorial waters and reinforces the security and environmental protection of the U.S.-based cable landings.

Key Regulations, Compliance Standards, and Safety Protocols

To safeguard both marine environments and cable systems, strict regulations and protocols govern submarine cable operations worldwide. Regulations for submarine cables include environmental assessments, safety inspections, and compliance with international marine standards.

These protocols are essential for minimizing ecological impacts and protecting the cable from potential damage, thereby ensuring secure data transmission. Compliance standards often require cable operators to undergo regular monitoring and maintenance checks. These ensure that cables remain operational and resilient to threats. 

Additionally, some regions have unique standards based on local environmental sensitivities, requiring further adaptation by operators to protect the marine habitat. Such comprehensive regulation not only enhances the durability of submarine cables but also safeguards ocean biodiversity, reflecting a balance between technological advancement and environmental responsibility.

The most important protocols for submarine cable operations include:

• Environmental Impact Assessments (EIA): Before installation, operators are required to conduct comprehensive environmental assessments to identify potential impacts on marine ecosystems, particularly on sensitive habitats like coral reefs and seagrass beds. EIAs help establish cable routes that minimize disruption to marine biodiversity.
• International Cable Protection Committee (ICPC) Recommendations: The ICPC provides a set of globally recognized best practices for submarine cable protection, including guidelines for cable burial depths, routing to avoid environmentally sensitive areas, and periodic monitoring to ensure cable integrity.
• Marine Protected Areas (MPA) Compliance: In certain regions, submarine cable routes must adhere to regulations specific to Marine Protected Areas, which may involve restricted cable installation and maintenance activities to protect vulnerable ecosystems.
• Seabed Mining and Fishing Regulations: To prevent physical damage from activities like seabed mining and commercial fishing, protocols include buffer zones around cables and restrictions on fishing equipment and anchoring near cable routes, reducing risks of cable interference and breakage.
• Regular Inspection and Maintenance Protocols: Compliance standards mandate routine inspections of cables, particularly in high-risk zones, to ensure structural integrity. Maintenance protocols cover emergency response strategies for immediate repairs to damaged sections, minimizing potential service disruptions.

Importance of Regulatory Oversight

Given the critical nature of submarine cables for global communications, regulatory oversight plays a crucial role in their safe and efficient operation. Operational security, data integrity, and environmental protection are paramount in submarine cable regulation. 

New cables are seen to be added to existing ones. Oversight ensures that submarine cables remain functional and safe, reducing the risk of data interruptions, protecting sensitive information, and minimizing environmental impact. Regulations also mitigate geopolitical risks associated with transnational infrastructure, supporting stability in the global communications network.

Additionally, regulatory frameworks help ensure that response protocols are in place for potential damage or breaks, minimizing downtime and disruption. By requiring adherence to established standards, regulatory bodies contribute to the global network's resilience.

Frequently Asked Questions

Do we still use submarine cables? 

Yes, submarine cables remain essential. Despite advancements in satellite technology, submarine cables carry over 95% of international data traffic, making them indispensable for high-speed, high-capacity internet and communications.

What happens if an undersea cable breaks? 

When a submarine cable breaks, repair ships equipped with advanced equipment and expert crews are dispatched to locate and repair the break. The repair ship can access the cables even at great depths, using remotely operated vehicles (ROVs) or grappling hooks to bring the damaged sections to the surface, where technicians then splice and repair the damaged cables.

How many miles of undersea cables are there? 

Today, submarine cables span over 1.4 million kilometers, linking continents, countries, and islands across the globe. This extensive network forms the foundation of global internet connectivity, allowing for seamless data exchange between North America, Europe, Asia, Africa, and Australia.

What is the lifespan of undersea cables?

Most submarine cables are designed to last 20 to 25 years, although some may continue to operate beyond this with periodic maintenance. After this period, the cable’s optical fibers may experience degradation. As technology advances, older cables may be decommissioned or upgraded to support faster data transfer speeds or higher capacity.

How much does it cost to install submarine cables?

The installation of a submarine cable is a complex and costly process, with expenses typically ranging from $100 million to $500 million, depending on factors like cable length, capacity, and geographic location.

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