Submarine Communication Cables
Submarine cables are the physical backbone of the internet, carrying the overwhelming majority of data that crosses oceans between continents. TeleGeography tracks more than 600 active and planned systems stretching over 1.5 million kilometers. These figures reflect TeleGeography's 2026 data, drawing on the Submarine Cable Map and Submarine Cable FAQ.
Key Submarine Cable Insights
Cables, not satellites, run the internet
FCC data cited by TeleGeography shows satellites account for just 0.37% of all US international capacity, meaning submarine cables carry essentially all the rest. The cliché that cables handle over 99% of intercontinental traffic holds up.
A record cable-building boom
TeleGeography tracks more than 600 active and planned cable systems as of 2026, up from around 300 a decade earlier. New systems entering service between 2025 and 2027 are forecast to be worth over $13 billion, nearly double the prior period.
Most faults come from fishing and anchors
The International Cable Protection Committee, cited by TeleGeography, records roughly 200 cable faults a year. About two-thirds stem from external aggression, mainly fishing vessels and dragged ships' anchors, with earthquakes and abrasion behind most of the rest.
Big Tech now builds the cables
Content and cloud providers, Google, Meta, Microsoft and Amazon, are now major cable investors. International capacity deployed by content networks nearly quadrupled to 3.6 Pbps between 2019 and 2023, and these networks drive almost three-quarters of bandwidth demand.
In-Service Submarine Cable Systems Over Time
The number of active submarine cable systems mapped by TeleGeography, from snapshots of its Submarine Cable Map. The count has roughly doubled in a decade.
Key Finding: TeleGeography tracked about 300 systems in 2015 and more than 600 active and planned by 2026.
Submarine Cable vs Satellite Share of International Capacity
Share of US international capacity carried by submarine cable versus satellite, based on FCC statistics cited in TeleGeography's Submarine Cable FAQ.
Key Finding: Satellites make up only 0.37% of US international capacity; submarine cables carry virtually everything else.
What Causes Submarine Cable Faults
Breakdown of the roughly 200 annual cable faults by cause, per International Cable Protection Committee data cited by TeleGeography. 'External aggression' is the industry term for fishing and anchor damage.
Key Finding: About two-thirds of all cable faults are caused by fishing vessels and ships dragging anchors.
Used International Bandwidth Growth
Total used international bandwidth in petabits per second, from TeleGeography's Global Bandwidth research. Demand tripled between 2020 and 2024 at roughly a 32% compound annual growth rate.
Key Finding: Used international bandwidth surpassed 6.4 Pbps in 2024, roughly triple the 2020 level.
Capacity Deployed by Content & Cloud Networks
International capacity deployed by content networks such as Google, Meta, Microsoft and Amazon. TeleGeography reports it nearly quadrupled in four years as these firms began funding and owning cables.
Key Finding: Content-network international capacity nearly quadrupled to 3.6 Pbps between 2019 and 2023.
Understanding Submarine Cable Data
What counts as a cable system
A submarine cable system is a single named project that may include multiple fibre pairs and several landing stations where it comes ashore. TeleGeography's count of more than 600 mixes in-service systems (about 570 as of 2025) with planned systems under contract or construction (around 80), so headline totals depend on whether planned cables are included. Branching units let one system serve many countries, which is why system counts are far smaller than the number of country-to-country routes.
Capacity: lit versus potential
A cable's design (potential) capacity is the maximum the fibre could carry if fully equipped; its lit capacity is what is actually switched on, and used bandwidth is lower still. Operators light capacity incrementally as demand grows, so a new cable can advertise huge potential while carrying a fraction of it. The bandwidth figures here track used international bandwidth, which reached over 6.4 Pbps in 2024, not theoretical totals.
Why traffic goes by sea, not space
Submarine cables beat satellites on capacity, latency and cost for intercontinental links: a single fibre pair can carry far more than entire satellite fleets, with lower delay. FCC data cited by TeleGeography shows satellites account for just 0.37% of US international capacity. Newer low-earth-orbit constellations add reach to remote and mobile users but do not change the basic picture that essentially all bulk intercontinental data moves through cables on the seabed.
Faults and repairs in context
The International Cable Protection Committee, cited by TeleGeography, records roughly 200 faults a year, about four a week, with around two-thirds caused by external aggression from fishing gear and anchors. Most faults are routine and barely noticed because traffic reroutes across the dense mesh of cables; specialised repair ships hook the damaged cable, raise it, and splice in a new section. Deliberate sabotage and shark bites are rare exceptions, not the norm.