The Cloud Under The Sea: the ships that repair undersea cables
April 16, 2024 5:48 PM   Subscribe

The world’s emails, TikToks, classified memos, bank transfers, satellite surveillance, and FaceTime calls travel on cables that are about as thin as a garden hose. There are about 800,000 miles of these skinny tubes crisscrossing the Earth’s oceans, representing nearly 600 different systems, according to the industry tracking organization TeleGeography. The cables are buried near shore, but for the vast majority of their length, they just sit amid the gray ooze and alien creatures of the ocean floor, the hair-thin strands of glass at their center glowing with lasers encoding the world’s data. If, hypothetically, all these cables were to simultaneously break, modern civilization would cease to function.

A long, fascinating piece about undersea cables, how they get damaged, and how they get repaired.
posted by the duck by the oboe (20 comments total) 46 users marked this as a favorite
This is really interesting, thank you!
posted by tiny frying pan at 6:40 PM on April 16 [1 favorite]

Good time to link to The Digital Antiquarian's A Web Around the World series that covers the invention of telegraph and laying of the first undersea cables. Pro tip: Get a quality cable and a nautically-rated strain-relief system.
posted by credulous at 6:48 PM on April 16 [1 favorite]

One of the best pieces of writing I've ever read on this topic, although it's dated now, is Neal Stephenson's (very) long-form feature article Mother Earth Mother Board for Wired from 1996 (Jesus, I'm old), which outlines the history, technology, function, and societal implications of long-haul communications lines. He actually travelled on the ships that lay the cables and visited various locations all across the globe for this, and it's very thorough and interesting. I highly recommend it.
posted by Joakim Ziegler at 6:56 PM on April 16 [20 favorites]

It is a really good article but the graphics make it really hard to read on my phone. May have to read it later on the computer.
posted by Peach at 7:05 PM on April 16 [1 favorite]

Despite many voices claiming that it was all science fiction end Elon vaporware and obviously impossible, SpaceX has actually got its sat-to-sat laser mesh thing working now or so I hear; so they're no longer totally reliant on ground station links to move data across the planet. Won't be long before Amazon gets theirs going as well. Not saying that either of these will have anything like the capacity of the undersea cables any time soon, but there's now at least some redundancy in place.
posted by flabdablet at 7:21 PM on April 16 [2 favorites]

Incidentally, "nautically-rated strain-relief system" would make an excellent username.
posted by Greg_Ace at 7:51 PM on April 16 [2 favorites]

For a short but informative and also entertaining and amusing overview, check out Jay Foreman/Map Men's Internet Vs Ocean: the essential wires we never think about. However unless you have very high-speed ears I recommend a .75 playback speed because their videos, shall we say, do not linger.
posted by Greg_Ace at 8:07 PM on April 16 [3 favorites]

Utterly fascinating article about a topic i did not think would be fascinating. The technology! The people! The geopolitics! The corporate scheming!
posted by congen at 8:53 PM on April 16 [1 favorite]

Having read multiple times over the last few decades (!?!) the Mother Earth Mother Board article (short book?) Joakim Ziegler linked to, I had envisioned cable repair ships and crews as a scrappy lot that made good money and spent it living large when in port between emergencies, kind of like a cross between pirates and mercenaries.

This piece paints what is, I think, a much more realistic picture of stressful, difficult work that like most other work in this world, is facing down a short-term future of uncertainty at the hands of capital.

It was a great read, but I'm sad my image of the business has been changed so much.
posted by Ickster at 9:03 PM on April 16 [5 favorites]

Thanks for that Joakim Ziegler, I was going to mention it myself, but you beat me too it.
posted by Relay at 10:41 PM on April 16 [1 favorite]

The Verge article (which is great!) also mentions this essay, Rethinking Repair [PDF], by Steven Jackson, which I found to be fascinating.
posted by chavenet at 12:46 AM on April 17 [2 favorites]

I'll be surprised if that doesn't turn out to be the best thing I read on the web today.
posted by Molesome at 2:34 AM on April 17 [2 favorites]

Thanks for this great post!

I wonder if there are any replacement plans in place that don't involve more undersea cables - i.e., satellites that are slowly taking the place of cables as time goes on.

a cable laid in 1858...prompted celebrations so enthusiastic that revelers set fire to New York City Hall

I'm imagining people happily burning down Apple's big California campus after getting very low ping with servers across the ocean one day.
posted by somebodystrousers at 8:48 AM on April 17

This was fantastic, thank you for sharing! Wish I could read an article this good every day!
posted by donuy at 12:16 PM on April 17

That was great, thanks!

I wonder if there are any replacement plans in place that don't involve more undersea cables - i.e., satellites ...

With experience and authority, I can assure you that the terrestrial (fiber) connectivity bandwidth utterly dwarfs anything that space assets can offer. Even Starlink's most lofty ambitions, much less what they are operating now, don't come close to even 1% of what the global fiber network does. Satellite technology has unique value, sure, in a) reach, b) speed of deployment and c) one-to-many broadcasting. But for the sheer volume of data that our current society consumes, it has to be fiber. The bits-carrying capacity of modern fiber is truly eye-watering.
posted by intermod at 8:51 PM on April 18 [3 favorites]

Tapping that experience and authority: why is the data rate available on a fibre link so large compared to that of a free-space laser link? How much better would laser collimation need to get before the beam-divergence loss in a free space laser degrades the available signal-to-noise ratio less than the imperfect-transparency loss in a single-mode fibre? Or is fibre in fact already more transparent than space at the altitudes Starlink operates at? Or am I thinking about this the wrong way entirely - is the issue not so much the links themselves, as the amount of energy available for throwing at endpoint signal processing?
posted by flabdablet at 11:03 PM on April 18

flabdablet: fundamentally, energy requirements and beam collimation are the more tractable parts of the problem. Rear Admiral Doctor Grace Murray Hopper explained the less tractable part, albeit indirectly, in her delightful famous bit about nanoseconds (Youtube link, about 3 minutes long).

(Even at the altitudes LEO satellites operate at, space is a long way away, comparatively. You're just not going to get acceptable latency for most things with a mandatory roundtrip all the way to space and back.)
posted by adrienneleigh at 1:46 AM on April 19 [1 favorite]

Latency might be much less of an issue than you seem to think.

Signals in optical fibre propagate at lightspeed / refractive index, about 1.5 for fibre so about 200km/ms. If I'm in Melbourne and exchanging packets with a service in New York, then even assuming a fibre running directly between those cities along a great circle, that's about 17,000km for a path delay of 17,000/200 = 85ms.

Starlink satellites orbit at 550km. Signal path from user terminal to satellite is essentially free space, so signals propagate at lightspeed: 300km/ms, so roughly 2ms path delay each way.

The extra 550km of radius means that a geodesic path across the Starlink mesh is going to be about pi * 550km longer than a great circle on the surface, so say 19,000km Melbourne to New York. But all those signals also propagate at the speed of light in free space rather than in glass, so the path delay comes to 19,000/300 = 63ms. Add on a pair of 2ms terminal-to-sat delays and that's 67ms, which is still a lot less latency than the fibre.

Obviously the prevalence of local CDNs is going to avoid globe-spanning delays for the bulk of Internet traffic, but an extra 8ms of satellite-inherent ping latency is nothing like a showstopper especially when so much of the terrestrial competition is so completely shit. My own Starlink connection, for example, is currently showing 21-35ms ping times to, while my National Broadband Network land-based fixed wireless connection needs 45-55ms to ping the same Sydney server (
posted by flabdablet at 2:56 AM on April 19

When thinking about what LEO constellations like Starlink can do, it's important not to think of them as in any way akin to old-school geostationary satellite Internet. Geostationary sats orbit at about 36,000km rather than 550, making ground-to-sat signal transit time close to 120ms rather than 2. Stacking four of those delays end-to-end to complete a full ping adds half a second of latency even for servers located physically close on the surface, and there really is no getting around that.
posted by flabdablet at 3:14 AM on April 19

Mod note: Just down here zipping through the tubes, adding this post to the sidebar and Best Of Blog!
posted by Brandon Blatcher (staff) at 7:15 AM on April 19

« Older Got WiFi? Will Spy   |   Meat asks the trivia questions. Newer »

This thread has been archived and is closed to new comments