← Daily DoseThe Glass Between Us — Daily Dose No. 046
Daily Dose / Aug 30, 2026 / Undersea Cables
The Glass Between Us
Almost everything you call "the cloud" is actually a bundle of hair-thin glass fibres lying in the dark on the ocean floor. About six hundred cables — most of them no thicker than a garden hose — carry more than 99% of the data that moves between continents. Satellites carry the rounding error.
1.5 million km
of submarine fibre-optic cable in service worldwide as of early 2026 — enough to circle the equator 37 times, or to run to the Moon and back nearly twice. Source: TeleGeography, 2026
01 / The scale
Six hundred threads hold the internet together
Every transoceanic video call, trade settlement and model training run crosses one of a surprisingly small number of physical objects. The whole intercontinental internet is a countable set.
600+
Active & planned cable systems
99%+
Of intercontinental data traffic
0.37%
Share of US international capacity via satellite
$10tn
Financial transactions carried per day (est.)
Sources: TeleGeography submarine cable database, 2026; FCC international capacity filings via TeleGeography, 2023. The $10 trillion figure is an estimate, derived by TeleGeography (2023) from SWIFT daily message volumes and average message value — order-of-magnitude, not a measurement.
02 / The spectrum
Down the shelf, onto the abyssal plain
Close to shore, cables are armoured and ploughed into the seabed. Past the continental shelf the armour comes off: on the deep plain a transoceanic cable is about as thick as a garden hose, and it simply lies there, unburied, under four kilometres of water.
0 m
Landing station buried 1–3 m
1,000 m
Shelf edge armour ends
3,682 m
Mean ocean depth NOAA
6,000 m
Abyssal plain
8,000 m
Deepest cable laid
The light-carrying fibre itself is about the diameter of a human hair; the rest is steel, copper and polyethylene. Sources: TeleGeography submarine cable FAQ, 2026; NOAA mean-ocean-depth figure (3,682 m); ICPC.
03 / The trend
Thirty-six calls, then three billion
In 1858 the first transatlantic telegraph cable carried a 98-word greeting from Queen Victoria to President Buchanan. It took about sixteen hours to send, and the cable died within weeks. Here is what the same ocean crossing has carried since — measured in simultaneous voice calls.
Circuit counts are documented system capacities: TAT-1 (1956) 36 voice circuits; TAT-3 (1963) 138; TAT-6 (1976) 4,000; TAT-8 (1988) 280 Mbit/s ≈ 40,000 circuits; TAT-14 (2001) 640 Gbit/s per route; MAREA (2017) 200 Tbit/s design capacity. Conversion of the fibre systems into "voice calls" at 64 kbit/s per call is illustrative, used only to put eight orders of magnitude on one axis. Sources: IEEE / ETHW milestone records; Submarine Networks; Microsoft & Meta system specifications. Newer still: the 2Africa system completed its core in 2025 with 180 Tbit/s across 16 fibre pairs (Meta, 2025).
04 / What breaks them
Roughly two hundred breaks a year
Cable faults are routine, not exceptional. Most are nobody's plot: a trawl door, a dragged anchor, a submarine landslide. Sabotage is rare — but it is the category that has grown.
The International Cable Protection Committee's long-run average. With ~600 systems in service, that is a break somewhere in the network roughly every other day — and the reason cables are built in redundant sets, not one per route.
11 cables in 15 months
Damage to Baltic Sea cables between October 2023 and January 2025, in a string of incidents involving anchor-dragging vessels. NATO launched its Baltic Sentry patrol mission on 14 January 2025 in response.
Sources: ICPC via TeleGeography, 2026; Defense News, January 2025; NATO Allied Command Operations, 2025.
05 / The geography
The internet has narrow water
Cables cannot go everywhere. They follow the same few corridors that shipping has used for centuries — and pile up in a handful of straits where one anchor can reach several systems at once.
More than 90% of Europe–Asia communications transit Egypt and the Red Sea corridor (CSIS, 2024; Telecom Egypt). In February 2024 three cables — EIG, Seacom/TGN-EA and AAE-1 — were severed near Yemen, widely reported as disrupting about 25% of Europe–Asia traffic; one network operator later argued the real figure was far higher. AAE-1 was not fully restored until late July 2024.
06 / The stakes
When it breaks, you wait for a ship
There is no remote fix. A vessel must sail out, grapple a hair-thin fibre off the seabed, haul both ends to the surface, splice them, and lower the loop back down. The entire planet depends on a fleet you could park in one harbour.
38
Days Tonga spent cut off from the internet in 2022 after the Hunga volcano shredded its only cable. The repair ship replaced about 92 km of an 827 km line.
~5
Months the AAE-1 cable stayed broken in the Red Sea in 2024 — cut in February, restored in late July, delayed by permits and risk to the repair crew.
$3bn
Estimated cost of replacing 15 ageing cable-maintenance ships and adding capacity by 2040, per a 2025 industry study.
Ships worldwide that lay or repair subsea cable
60
Dedicated to repair (often converted tugs & ferries)
22
Of the 60, already over 30 years old
19
Of the 60, younger than 18 years
8
Bar lengths scaled to the 60-ship total. One vessel in the fleet, Finland's Telepaatti, was built in 1978. Sources: Scientific American, 2025; DatacenterDynamics fleet analysis, 2025; 2025 industry replacement study.
Why it matters
Redundancy is the whole strategy
Nothing about this is wireless. 5G, satellite constellations and "the cloud" all hand off to glass on the seabed within milliseconds. Satellites carry well under 1% of international capacity.
Resilience is route diversity. A country with one cable — Tonga, and dozens of island states like it — is one anchor away from going dark. A country with six is inconvenienced, not severed.
The bottleneck is ships, not fibre. New cables are being funded at record rates; the repair fleet that keeps them alive is small, ageing and barely being replaced.
Watch the corridors. The Red Sea, the Luzon Strait and the Baltic concentrate enormous traffic into narrow water. New routes around them — via the Arctic, around Africa, overland — are the quiet infrastructure story of the decade.
Sources & notes
TeleGeography (2026) — Submarine Cable FAQs & cable database: 600+ active and planned systems; over 1.5 million km in service; cable "as wide as a garden hose"; fibres "roughly the diameter of a human hair"; ~200 faults per year per ICPC; two-thirds of faults from fishing gear and anchors.
US FCC international capacity filings, via TeleGeography (2023) — satellites account for 0.37% of US international capacity.
TeleGeography (2023), "Do $10 Trillion of Financial Transactions Flow Over Submarine Cables Each Day?" — estimate, derived from SWIFT daily message volumes × average message value. Illustrative order of magnitude, not a measured total.
NOAA — mean ocean depth of 3,682 m. Deep-water cables are laid to roughly 8,000 m (ICPC / TeleGeography).
Submarine Networks — TAT-14 (2001), 640 Gbit/s per route. MAREA (2017), 200 Tbit/s design capacity, 8 fibre pairs.
Meta Engineering (Nov 2025) — completion of the core 2Africa system; up to 180 Tbit/s across 16 fibre pairs.
Library of Congress / IEEE Spectrum — 16 Aug 1858: Queen Victoria's 98-word message to President Buchanan took roughly 16 hours over the first transatlantic telegraph cable, which failed within weeks.
Defense News (Jan 2025) and NATO Allied Command Operations — 11 Baltic Sea cables damaged in 15 months from October 2023; Baltic Sentry mission launched 14 Jan 2025.
CSIS (2024) & Telecom Egypt — over 90% of Europe–Asia communications transit Egypt and the Red Sea corridor.
Reuters / AP / NPR (Feb 2022) — Tonga restored after 38 days; repair ship replaced ~92 km of the 827 km Tonga–Fiji cable.
Light Reading / Submarine Networks (2024) — Feb 2024 Red Sea cuts to EIG, Seacom/TGN-EA and AAE-1; ~25% of Europe–Asia traffic widely reported (operator RETN later argued the impact was far larger); AAE-1 restored late July 2024.
Scientific American (2025) & DatacenterDynamics — ~60 cable ships worldwide, 22 dedicated to repair, 19 over 30 years old, 8 under 18; ~$3bn estimated to replace 15 vessels by 2040 (2025 industry study).
Note on the trend chart: converting fibre-system bit rates into "simultaneous voice calls" at 64 kbit/s per call is an illustrative normalisation, not a manufacturer specification.