The Matsu Islands are an archipelago of 36 islands in the East China Sea, alongside the southeastern shoreline of mainland China. The islands have been administered since 1949 by Taiwan, part of a larger set of outlying islands administered by Taiwan, which includes the Kinmen and Penghu Islands, which all lie in the Taiwan Strait.
The Matsu Islands are connected to Taiwan’s chief isle by two submarine cables — Taima No.2, Taima No.3, and shortly Taima No.4. The Taiwan Strait is a shallow build of water, alongside an average degree of 70m. The submarine cables that lie on this seafloor are susceptible to damage from ship-based activity, akin being snagged by fishing equipment or anchors. But these particular cables have been remarkably unlucky. Between 2018 and 2022, the submarine cables between Taiwan and the Matsu Islands were cut 27 times, and there have been four important outages in the three years from 2023 to 2025.
That’s not the lone location anywhere submarine cables have suffered many faults. The Baltic Sea is a shallow sea that has a dozen or so submarine communications cables, and undersea power and gas pipelines. There have been 11 disruptions to these submarine systems since 2023. Again, a extremely unlucky track record.
There are an estimated total of 1.5M kilometres of subsea communications cables, used by 607 in-service submarine cable systems (Figure 1) that are crucial to the world’s telecommunications services. If they are put out of assistance for any reason, our moon systems merely could not substitute them. In specified a catastrophic scenario, several communities would be totally isolated, alongside serious logistical and financial ramifications.
We regard this gathering of submarine cable systems as crucial infrastructure for earth communication services, and we obtain attention to create them as resilient as possible. Modern war can deliberately disrupt communications systems, which adds another origin of possible damage to the catalog of geological and unintended risks facing subsea cables.
On the night of 4 August 1914, days following Britain declared war against Germany, the British cable container HMTS Alert sailed from Dover into the English Channel. The container dragged grappling hooks alongside the seabed, hauled up five German transatlantic and European telegraph cables, and cut them. This severed Germany’s direct, safe submarine cable links to the Americas, Africa, Spain, and the remainder of Europe. Germany was forced to depend on wireless broadcast transmissions, anywhere British intellect could readily eavesdrop. If the German cryptography used to defend these wireless communications was broken, afterward it allowed the British to track armed forces movements and grasp crucial messages, specified as the Zimmermann Telegram.
This identical act to deliberately sever undersea cables was repeated by the British in September 1939, cutting German cables to Lisbon and New York.
Protecting the cable
These lean polyester-coated cables at the base of the sea are vulnerable, including to:
- Geology in the form of submarine earthquakes or landslips
- Being snagged by dragging container anchors or fishing equipment alongside the seafloor
- Deliberate attacks on the cables alongside grapnels and cutting equipment
How can cables defend against specified risks? The inner center of the fiber optic cables and its copper conductor sheath can be wrapped in additional layers of alloy cable jacketing as a form of armour (Figure 2). This is mostly used to decrease its exposure to shipping accidents.
Figure 2 is slightly misleading. What is depicted current is a cross-section of submarine cable used in the segments of the cable that guide to the exterior cable station. The cable segments that are laid on the deep-sea flat use fair the inner components: Optical fiber and a sole lean alloy thread wrapped in a silicone gel, surrounded by a copper sheath (used to power the cable repeaters), and wrapped in polyethylene. There are no external armour elements. These deep-sea cable segments are about 20mm in diameter, or the size of a storyline hose.
The cable surfaces at a cable landing station. These landing stations are typically plain, secured accommodation alongside dependable power. The preferred location is a coastal item alongside a low quantity of fishing or another maritime traffic, and a steep increase from the deep-sea floor. Cables are at their top hazard from coastal shipping activity, so the shorter the extend from the deep-sea flat to the cable position on dry land, the better.
Many jurisdictions additionally province ‘Cable Protection Zones’ as a alert to marine container operators that there are cables on the seafloor in this area, and ships should refrain from fishing action and anchoring in these areas.
Cable routing
Cable routing is additionally crucial in conditions of resilience. There are multiple objectives in a cable route, and not all of them can be optimized at the identical time.
The cable path have to be as abbreviated as possible, as additional cable dimension raises chief expenses and increases end-to-end indication delay.
Cables should evade areas of energetic geological action anywhere possible, specified as tectonic dish boundaries and mid-plate rifts. Deeper is better, but inside reason. Cables on the flat of a profound sea division are small susceptible to shipping action and antagonistic efforts to disrupt the cable, but alongside extreme depths it’s additional challenging to find and lift the cable whenever undertaking a repair.
Sometimes there are geographic ‘choke points’ through which many cables are routed. The Bab al-Mandab Strait is not fair a choke item for exterior vessels passing between the Indian Ocean and the Red Sea, but it is additionally the conduit through which 16 cables continue (Figure 4). In September 2025, multiple cables were severed in the Bab al-Mandab Strait, disrupting an estimated 25% of cable capability between Asia, Europe, and the Middle East. Houthi-controlled waters remain efficiently ungovernable for cable protection.
There is additionally the Singapore Strait, a important junction for 35 cable systems (Figure 5). This is a shallow h2o strait that additionally hosts a important quantity of exterior shipping.
Further north, between Taiwan and the Philippines is the Luzon Strait, anywhere 18 cables continue (Figure 6). This was the location of an earthquake and a consequent set of submarine landslides in December 2006 that not lone severed all the cables operating through this strait, but additionally buried many of them under profound layers of sediment. It took 11 repair vessels 49 days to bring all the cable systems rear into operation.
The Black Sea is an area alongside geopolitical hazard and regulatory gaps. While quarry hazard is confirmed, no cable faults have been immediately documented in the war in Ukraine. Russia’s continued existence and the battle create this area functionally inaccessible for regular cable maintenance.
Geopolitics additionally plays a function in cable routing. Cable owners volition favor to evade routes through politically unstable territorial waters if suitable substitute routes exist. There are additionally governmental considerations. If a cable lands in US territory, afterward the cable is topic to multiple Federal Communications Commission (FCC) constraints, including banning equipment or services from companies the FCC see as a danger to US national security. The FCC has additionally refused to authorize the landing of a cable on US district if the cable additionally lands in a district that the US deems to be a abroad adversary.
Land routes are avoided in general, but there are several circumstances anywhere a district path is the preferred option. Connectivity between Asia and Europe would normally run through the Bab al-Mandab Strait, landing in Egypt in the Gulf of Suez, afterward overland through Egypt to get to the Mediterranean Sea. There is an substitute path through the Persian Gulf, Iraq and Türkiye, although this entails a section that transits the Strait of Hormuz, or a second overland section through Oman and the United Arab Emirates.
Cable faults
Around 200 submarine cable faults are reported worldwide all year, a fig that the International Cable Protection Committee notes has stayed broadly dependable in latest years equal as the total cable inventory increases. The cables themselves are remarkably reliable. It is the maritime traffic complete them that is the logic of most of the problems. 86% of cable faults are apt because of fishing action or anchoring, and fishing action is about twice as prevalent as anchoring incidents.
Geological events, specified as submarine landslides and seabed movement, document for concerning 7% of cable faults, cable abrasion for 4%, and component nonaccomplishment (in repeaters) for lone 4%.
With the elevated association of faults and maritime activity, it is not amazing that fair under one fractional of cable faults happen in territorial waters, and most of the remainder happen in exclusive financial zones. Just 2% happen on the elevated seas. Cables are most susceptible near to shore, in shallow water, anywhere fishing is concentrated, anywhere ships anchor, and anywhere the cable must arrive ashore at a landing position alongside all another cable serving that coast. The profound ocean, anywhere there is small seabed fishing action and few ships anchoring, is the safest location for a cable.
National jurisdictions do not halt at the low tide grade of a territory, they broaden out into the sea and the seafloor. The 1982 United Nations Convention on the Law of the Sea (PDF) defined sovereign territorial waters as a 12-mile area extending out from an economy’s coast. Every coastal economics has exclusive entitlements to the oil, gas, and another resources in the seabed up to 200 nautical miles from coast or to the external border of the continental margin, whichever is the further, topic to an general bounds of 350 nautical miles (650km) from the shoreline or 100 nautical miles (185km) beyond the 2,500-metre isobath (a row connecting equal points of h2o depth).
What does this average for submarine cables? From the item anywhere the cable enters territorial waters, any bodily action connected to the cable requires the approval of the authorities. All cable building and repair operations carried out in these sovereign areas additionally necessitate the approval of the economics that has exclusive entitlements to the sea and seafloor.
Location and repair
Locating a cable interrupt is straightforward. An optical beat volition be reflected at the item of a cable break, which can provision the extend to the error from the commencement of the cable alongside significant precision. At that point, it becomes a marine operation.
A expert cable repair container must be engaged, which, in turn, must get the applicable government’s approval to activity at the location of the cable error (don’t ignore that lone 2% of outages happen in global waters). Once at the interrupt location, the repair container drags a grapnel alongside the seabed to hook the cable, cuts it, recovers one end, buoys it off, afterward recovers the another end. A new division is spliced into the cable aboard the container in a jointing cabin, the fiber fusion-spliced and tested, the shared rebuilt and sealed against pressure, and the repaired cable laid rear downward alongside adequate slack to attain the seabed.
The disbursal of a repair can change greatly, depending on the location and degree of the fault, the nature of the contracted arrangements for cable repair, the amount of period the cable controller is consenting to delay for a repair container and crew, and the weather. USD 500k to USD 1M is a delegate disbursal of a sole cable repair.
While the figure of cables has grown, the period taken to get approval to run repairs in territorial waters has mostly increased. Industry data indicates repair reply times have additional than doubled complete the former decade, and the longest sole repair recorded in 2023 took 947 days, many of which were spent waiting for approval to undertake the repair.
There is additionally the matter of repair vessels. The industry has approximately 60 ships capable of repairing a submarine cable, operated under care agreements that pond the disbursal of operating this fleet throughout cable owners in all geographic region. These company Submarine Cable Maintenance and Repair Agreements are used in the Atlantic Ocean, the North American Western Coastal region, the Mediterranean, South East Asia and the Indian Ocean, and Yokohama in the North Pacific (Figure 7).
Analysis by TeleGeography and Infra-Analytics has established that about two-thirds of cable care vessels volition attain the end of their assistance lives by 2040, during total cable kilometres are projected to develop by concerning 48% complete the identical period. Closing that gap would obtain USD 3B and necessitate fifteen replacement ships affirmative five additional vessels merely to clasp current assistance levels as the submarine cable network expands. The contiguous issue is that nobody evidently owns this bill. Cable care is funded through shared agreements that have been optimized for decades to be as cheap as possible, which worked whenever the fleet was young and is exactly the incorrect construction for financing a fleet renewal.
This is the center of the cable resilience problem. Adding cable routes is comparatively easy, since today’s hyperscale haze companies prosperity much of the new building themselves and have powerful business reasons to do so. However, no idiosyncratic cable is so crucial that it can prolong a endeavor case to run a dedicated repair fleet. The industry uses pooled resources, which endure from under-investment.
Investigating cable outages
A rundown of latest cable outages includes:
- Subsea cables were damaged in October 2023 by the anchor of the Hong Kong-flagged Newnew Polar Bear functioning in the Baltic Sea.
- Three cables in the Red Sea were cut in February 2024 by the drifting Rubymar container following it was struck by a missile.
- The C-Lion1 and the BCS East-West Interlink cables were cut in the Baltic Sea in November 2024 alongside the Chinese bulk transporter Yi Peng 3 nearby.
- Four cables were damaged in December 2024, alongside anchor drag marks on the Baltic seabed and the Cook Islands-registered tanker Eagle S detained.
- Taiwan recorded incidents in January and February 2025 on the Matsu cables.
- Three important cables, including SEA-ME-WE 4 and IMEWE, were cut in the Red Sea in September 2025.
- Finland and Estonia misplaced connections again in December 2025, alongside anchor drag confirmed by March 2026 on Baltic cables.
- In August 2026, the Indigo West and Indigo Central cables off Perth were damaged, alongside a UAE-managed tanker under inquiry by Australian Federal Police.
The outcomes are much small uniform than this catalog suggests. Swedish authorities established no conclusive evidence of wrongdoing in the Yi Peng 3 case and ruled the January 2025 Latvia-to-Gotland damage accidental. A Finnish court dismissed the case against the Eagle S captain in October 2025. United States and European officials concluded that multiple of the Baltic incidents were accidental. The captain of the Hong Tai 58 was convicted in Taiwan and sentenced to three years complete the Taiwan to Penghu No. 3 cable, and the Newnew Polar Bear captain faced offender damage charges in Hong Kong. The April 2026 Matsu error turned out to have been caused by the wreck of a stranded fishing container shifting onto the cable.
Anchor dragging is a average occurrence, particularly among poorly maintained merchant vessels in bad weather, accounting for a ample portion of average faults all year. This may explain why investigators keep reaching inconclusive findings in fine faith.
Who is liable for cable resilience?
Cable systems have changed in latest decades.
The old phone scheme regarded all cable as a self-contained system. The cable owner was liable for its own resilience, autonomous of any another cables that may be on akin routes. The telephone’s data wagon scheme typically used a circle architecture, anywhere any outage in the circle caused the traffic to stream alongside the another fractional of the ring. If the circle used varied paths, afterward any idiosyncratic outage in the circle could be repaired immediately.
However, the conclusion of this scheme was that the genuine capability of the scheme was twice the usable capacity. The disbursal of using specified a cable reflected this 50% wagon efficiency.
In their hunt for cheaper services, Internet Service Providers (ISPs) wanted to acquisition non-backed-up cable capacity, at a cost that reflected this greater effectiveness of cable use. They purchased this cheaper form of cable capability on multiple cable systems. Individual outages caused a interrupt in that cable’s service, but the ISP could reroute their traffic to use capability that had been purchased on another cable systems which were not affected by the outage. For Internet traffic, this failover function is readily achieved in the routing system.
The general outcome was that the duty for resilience shifted from the idiosyncratic cable controller to the network operator. Cable outages would motionless logic a autumn in accessible capacity. But as most Internet traffic is elastic, the autumn in capability would logic a autumn in achievement but not logic a complete shutdown.
Resilience and crucial infrastructure considerations
Submarine cable systems are built by personal consortia, repaired by personal contracts that collectively prosperity a business repair fleet, regulated by coastal states individually, and governed internationally by global conventions drafted lengthy before the Internet existed.
It would be fine if permissions to repair submarine cables were granted in a streamlined manner so that repairs were not stalled for months awaiting a government’s endorsement to run in their waters. It would be equal improved if emergency procedures were accepted ongoing fairly than negotiated during an outage.
Collectively, the industry needs to allocate in repair capability to upgrade an ageing repair fleet. Who undertakes this funding and how the repair capability is managed as a average asset is proving to be a difficult issue. In the worst case, it volition be rear to all cable for itself, and the inevitable outcome of higher expenses and possibly slower repairs.
Geographic choke points volition persist, earth discipline volition not stop, extreme climate and changing sediment conditions volition continue to stance a danger to these cables. Route assortment is an productive reply to these challenges, but financial clustering plant against cable path diversity. Each cable would akin to run through the shortest and cheapest route, and no cable controller is specifically motivated to expend additional sums to obtain a varied path to the another existing cables.
None of this is technologically difficult, but it can be institutionally and economically difficult, which is harder.
Looking forward
The phone business consortium example that funded and operated nearly all the world’s subsea cables 30 years ago has arrive to an end. The assistance existence of the complete inventory of cables and assistance vessels that they operated is additionally coming to an end.
Approximately a fourth of the world’s current subsea cable kilometres are projected to be decommissioned and former by 2030. This enormous withdrawal of capability amounts to 845,000 kilometres of subsea fibre-optic cables at the end-of-life sequence for submarine infrastructure laid during the enormous Internet surge of the delayed 1990s and first 2000s. Specifically, TAT-8 and TAT-14 in the Atlantic Ocean are being decommissioned, SEA-ME-WE-3, linking Europe and Asia, has been retired, and Japan-US and China-US have ended operations. In addition, additional than fractional of the current repair container fleet volition have reached their withdrawal item by 2040.
In their location are cable projects that are either completely funded or partially funded by the current US digital giants. This raises sovereign hazard eyebrows in many economies, anywhere the lone communications conduits for an economics are owned and operated by a abroad entity. It additionally raises the inquiry of sovereign authority complete the submarine repair container fleet and the existing care pooling arrangements through submarine cable care zones.
By 2028, Google volition own the largest set of cables, measured by kilometres, in the Pacific, Atlantic and Indian Oceans, and according to current plans it volition have additional than 50% of the complete cable inventory under its authority in the Indo-Pacific region. Similar centralization scenarios are playing out in the Atlantic Ocean as well. At this point, the sovereign hazard eyebrows have to be hitting the ceiling, as specified a foremost stance gives this sole business unilateral authority complete the care arrangements and connected repair container operations for the complete world’s communications network.
This is a grave matter for us, the two as individuals and societally as we try to maintain the integrity and usefulness of our average communications infrastructure. The stability and efficiency of our societies depend on our capability to communicate alongside all another seamlessly, efficiently and privately.
Passing the funding and operational expenses of the community telecommunications services from community to personal hands in the second part of the 20th hundred years was seen as a astute move. The move used personal backing to prosperity the reinvigoration of national telecommunications infrastructure as it shifted from time-based sound switching to a far larger packet switching architecture to assistance computer-mediated communications and assistance provision.
However, we may see additional uncomfortable outcomes looming in the near future. It was idea that the site of competition would rein in the possible abuses by personal operators of the privileged stance of functioning a community communications service. That is not what happened.
Not lone are community telecommunications systems now mostly in personal hands, but we are additionally seeing consolidation of the earth telecommunications scheme to a few personal entities, alongside no competition. Their accountability is not to the community or users of the service. Their accountability is to their organizational investors to continually enhance their value and profitability. Nothing else.
So anywhere does this depart the submarine cable scheme and efforts to keep its crucial function alongside the suitable levels of resilience that indicate their crucial function in earth communications? Outside the US, few idiosyncratic economies, if any, have the resources to meaningfully react to this challenge. The European Union (EU) has taken several act to contribute to backing a fleet of repair vessels and taken measures to enhance surveillance on submarine cables as a matter of local security, but no another economies appear to be following this lead. It would certainly be ironic if this EU prosperity were to end up merely backing the care of Google’s submarine cable assets!
Back to the topic of cable resilience, viewed at a earth level: Communications resilience is mostly an sea infrastructure question. Answers to this inquiry depend on:
- Detailed and current seabed surveys
- Shipping controls to forestall anchoring and seabed fishing in declared subsea cable safety zones
- A distributed repair fleet and crews trained to execute repair tasks
- Rapid clearance to run in territorial waters
Some coordination of act is necessary to open varied cable routes and evade sole points of exposure and possible failure. The earth cloud, for all its connotations of weightless air, firmly rests on the solidity of the seabed, and it can be no additional dependable than conventions that we collectively clasp to appearance following it.
The views expressed by the authors of this blog are their own and do not necessarily indicate the views of APNIC. Please note a Code of Conduct applies to this blog.
