June 8th marks World Oceans Day, and this is a global reminder of the oceans’ critical role in sustaining life, regulating climate, and connecting communities. Beneath the surface lies an unseen force driving our digital world: submarine cables.
These underwater fiber-optic cables span more than 1.4 million kilometers, connecting continents and enabling over 95% of the world’s international internet and voice traffic.
The Undersea Network: A Hidden Web of Global Connectivity
The concept of undersea communication dates back to the mid-1800s, when the first transatlantic telegraph cable was laid in 1858. Today, the global network has evolved into a dense mesh of high-capacity cables transmitting data at nearly the speed of light, making real-time international collaboration, cloud services, and global commerce possible.
These cables are designed to endure extreme marine conditions, including pressures thousands of meters below sea level, strong ocean currents, and temperature variations. They are typically about the width of a garden hose and armored in shallow areas to withstand physical hazards like fishing activity and ship anchors.
However, despite their resilience, submarine cables remain vulnerable to both natural and human-induced threats. In 2023 alone, cable outages caused by earthquakes and fishing incidents disrupted connectivity in regions like Southeast Asia, the Red Sea, and the Pacific Islands. For example, in October of the same year, Typhoon Koinu disrupted multiple cable routes between Taiwan and Hong Kong. In early 2024, damage in the Red Sea, suspected to be linked to geopolitical unrest, severed several cables, impacting internet traffic from East Africa to Europe and the 2024 African Coast Cables Disruption left millions across West Africa with degraded service for days due to deep-sea cable faults caused by suspected underwater landslides.
These incidents underscore the importance of continuous innovation in cable durability, route planning, and real-time monitoring systems.
Rising Tides, Shifting Challenges
As the climate crisis accelerates, the oceans are changing and so are the risks facing the critical infrastructure that lies beneath them. Rising sea levels are no longer a distant forecast; they are a present reality, reshaping coastlines and threatening the stability of undersea cable systems, especially where these cables make landfall.
Today’s cable landing stations (CLS) and nearshore routes face growing exposure to flooding, coastal erosion, and saltwater intrusion.
Areas once considered geologically safe are being reclassified as high-risk zones due to increased storm surges and shifting tidal patterns. For instance, severe flooding in Indonesia and Bangladesh inundated low-lying cable landing zones, prompting emergency shutdowns and rerouting of services.
Research published in Nature Communications has shown that more than 6,500 km of submarine cables and over 1,100 coastal landing stations could be affected by rising sea levels and storm surges by 2100, particularly across densely populated coastal regions like Southeast Asia and the U.S. East Coast.
As oceans rise, they bring with them stronger wave energy and the potential for increased sediment movement, which can dislodge or expose cables laid on the continental shelf. The result is an elevated risk of physical damage, service disruptions, and costly repairs.
These evolving threats demand a forward-looking, resilient approach to cable design and deployment. Strategies such as elevated landing station construction, deeper burial depths, and integrated coastal hazard mapping are already being explored and implemented by progressive players in the subsea industry.
Ocean Currents and Storms
Ocean currents play a dual role. On one hand, they help guide optimal cable routes by offering stable, navigable paths through the deep sea. On the other, their strength and variability can exert continuous stress on cables, especially in shallow shelf areas where cables are more exposed. Over time, this motion can lead to cable fatigue, suspension, or even abrasion as cables sway against rocky surfaces.
Storms amplify these risks dramatically. Increased wind speeds and wave action during tropical cyclones, hurricanes, and typhoons stir up sediment layers and accelerate seabed erosion, threatening even well-buried cables. Here are some examples to illustrate this rising danger:
- In the Mediterranean Sea, unusual storm surges forced emergency maintenance operations on shallow water cables near Southern Europe due to unexpected underwater landslides.
- Off the coast of West Africa, a combination of strong currents and sediment movement, triggered by seasonal storms, damaged four key cables (WACS, MainOne, SAT-3, and AC), severely impacting connectivity across several nations including Nigeria and Ghana.
- The Pacific Island nation of Tonga experienced disruptions due to turbulent ocean conditions exacerbated by Cyclone Gita, which stirred sediment and destabilized cable beds laid just two years prior.
Compounding this, climate change is intensifying weather extremes. Warmer ocean temperatures fuel more frequent and powerful storms, while shifting wind patterns alter the direction and force of long-established currents.
These changes are making traditional models for cable route planning and risk assessment less reliable, requiring continuous adaptation.
Tectonic Tensions
Along the ocean floor, tectonic forces silently reshape the planet, shifting continents, triggering earthquakes, and setting off submarine landslides. These natural movements pose a serious and often unpredictable threat to undersea cables, which are laid across some of the most geologically active regions on Earth.
Subsea cables must cross vast distances, including areas along the Pacific “Ring of Fire”, where tectonic plates collide with enormous energy. A single seismic event can rupture cables, damage coastal landing sites, or generate undersea landslides that bury or sever infrastructure in an instant.
For example, the Hengchun earthquake near Taiwan triggered underwater landslides that disrupted multiple undersea cables, causing widespread internet slowdowns across East Asia, while a 7.2 magnitude earthquake struck off the coast of Papua New Guinea, temporarily cutting off digital links between island communities and international networks due to cable breaks on the seabed and seismic activity in the South Atlantic led to a rare disruption in the South Atlantic Cable System (SACS), raising alarms over the need for deeper monitoring in lesser-studied fault zones.
Even distant earthquakes can set off turbidity currents—fast-moving underwater flows of sediment—that travel for hundreds of kilometers, sweeping up anything in their path, including cables. These currents are difficult to predict and harder to defend against, especially when they result from cascading geological and climatic triggers like heavy rainfall, floods, or coastal erosion.
In tectonically active regions, undersea cable resilience depends on both engineering foresight and ongoing scientific collaboration.
Cable designs must be reinforced, routes carefully studied for seismic risks, and monitoring systems put in place to detect early warning signs of geological stress.
Innovations Beneath the Surface
Innovation is rising to meet the challenge, transforming the very fabric of how submarine cables are designed, deployed, and protected. Modern engineering and scientific collaboration are driving a new era of ocean-smart infrastructure. Here are some of the key advancements shaping the future of subsea connectivity:
- Next-Generation Materials: Cables are now being constructed with corrosion-resistant alloys, reinforced polymer sheathing, and pressure-tolerant insulation, extending operational lifespans and enhancing performance under extreme pressure and temperature changes.
- Smart Monitoring Systems: Embedded Internet of Things (IoT) sensors and fiber optic strain gauges enable real-time health checks, detecting strain, movement, or temperature changes before they escalate into damage. These systems provide valuable early warnings and help prevent outages.
- AI-Powered Route Planning: Leveraging satellite data, oceanographic models, and machine learning (ML), engineers are now plotting cable paths that minimize exposure to tectonic faults, erosion-prone zones, and storm-intensified currents. This significantly reduces long-term risk and maintenance costs.
- Self-Burying Cables: In dynamic coastal areas and shallow waters, new cable types can automatically settle into the seabed over time, reducing exposure to fishing gear, anchors, or shifting sediments.
- Eco-Friendly Deployment Techniques: Modern cable-laying practices prioritize marine conservation by avoiding ecologically sensitive areas like coral reefs and seagrass beds. Some initiatives also explore biodegradable protection layers and low-impact burial tools to reduce ecological disruption.
Towards a Sustainable Subsea Future
Moving forward, the goals are clear: to innovate responsibly, invest wisely, and protect the ecosystems that make global connectivity possible.
As we conclude our reflections on World Oceans Day, it’s clear that the ocean is not just a vast natural resource but a vital enabler of our digital, economic, and social connections. The infrastructure we build beneath the waves carries more than data; it carries the weight of global progress.
