The Ineffable Importance of Undersea Cable Maintenance

Originally published at: The Ineffable Importance of Undersea Cable Maintenance - TidBITS

This must-read from The Verge weaves background about the undersea fiber optic connections that make the modern Internet possible with the story of what one maintenance ship went through repairing cables in the aftermath of the 2011 undersea earthquake off the coast of Japan.


Fascinating! There’s a whole deeply secret history of the US tapping Soviet cables during the Cold War with specialized submarines, only some of which has come to light. I assume efforts like that are ongoing now, by all sides.

(The US has a very expensive submarine that is explicitly designed for underwater espionage).


I second the recommendation of Blind Man’s Bluff. It’s a deeply interesting and well written book.


Me three…as a former fast attack submarine sailor…I knew in general about most of the things in it already but was shocked at seeing them in print. Somebody spoke when they weren’t supposed to methinks…usually the guys on the projects subs were pretty tight lipped about details. Of course…any attack sub sailor could tell a lot of good stories…but then we would have to shoot you because you’re not supposed to reveal any of that since it’s classified still.

1 Like

Great article. Thanks for the link.

A fourth recommendation of Blind Man’s Bluff. It is an eye opening read, and managed to get me interested in submarine & cold war history.

1 Like

A related story…a few years after reading this book, my spouse got to know one of the Commanders of a sub, USS Parche, that is extensively covered in the book. As you say, he would always deflect any questions about Parche with innocuous stories about training missions in the US or offshore stuff!


Funny story about the Parchee…which was the special projects boat before the Jimmy Carter was…Parchee actually was cut apart and an additional hull section welded in back in the 80s to give more space or intelligence gathering stuff.

Anyways…my ship was in Mare Island in overhaul and we attended the Submarine Birthday ball there. Normally a sub going in or out of dry dock is a pretty big deal and it’s an all hands evolution and the CO is personally in charge…but that’s for normal subs I guess. Parchee was in and out of dock so often that when they were scheduled to come out of dock the night of the ball all of their officers except the two duty officers were at the ball and the CO let the command duty officer and engineering duty officer with their duty sections handle the undocking. IIRC they hadn’t done anything that time in dock involving pressure hull integrity so as undockings go it was relatively minor…but still it seemed like a lot of trust in your duty officers to handle an evolution like that…at night…without any more senior supervision.

But yeah…the Parchee guys were pretty tight lipped…but then they got a Presidential Unit Citation almost every op they went on and generally speaking had fewer but far longer underway periods than those of us in the more regularly employed attack submarine force.


If the article leaves you wanting more, you should read Mother Earth Motherboard by Neal Stephenson (Mother Earth Mother Board | WIRED).

Harro de Jong

1 Like

For general background about the importance of fiber cable to the growth of the Internet, I recommend “Tubes: A Journey to the Center of the Internet” by Andew Blum. Although released in 2012 it has a superb explanation of how the Internet grew and the importance of fiber optic cables, landlings, telecom carriers and peer interconnects.

1 Like

A second recommendation for Stephenson’s wonderfully well-written piece from 1996. A bit of a travelogue, tech explainer, and history as Stephenson covers the route of a new cable. As the article’s lede summarizes:

IN WHICH THE hacker tourist ventures forth across the wide and wondrous meatspace of three continents, acquainting himself with the customs and dialects of the exotic Manhole Villagers of Thailand, the U-Turn Tunnelers of the Nile Delta, the Cable Nomads of Lan tao Island, the Slack Control Wizards of Chelmsford, the Subterranean Ex-Telegraphers of Cornwall, and other previously unknown and unchronicled folk; also, biographical sketches of the two long-dead Supreme Ninja Hacker Mage Lords of global telecommunications, and other material pertaining to the business and technology of Undersea Fiber-Optic Cables, as well as an account of the laying of the longest wire on Earth, which should not be without interest to the readers of WIRED.

1 Like

An archived pdf of Stephenson’s essay is here.

While I have no doubts that it might happen/be possible and not be public knowledge, the traditional way of tapping into a fiber cable, even above water, is challenging. I remember when fiber was first being utilized, even repairing fiber wasn’t really possible, it was always a replacement; usually when you pulled fiber there were always extra strands included for that reason.

Now it’s like an art form, that article even talks about the guy who only just does that. Also takes specialized equipment to make perfect joints. Doubt that could be done underwater without anyone noticing.

Case in point as mentioned in the article, they can locate those underseas breaks to the meter by timing signal bounce back from the termination points on shore. Pretty sure they could detect the degradation of intensity from a tap.

I have a vague memory of someone installing a tap or device in a fiber interconnect on the west coast years ago that made the news, but a quick search didn’t find anything. It was notable specifically because of how unusual it was given the technical challenges, and even then it might have been at one of the termination points, not mid fiber.

On a tangential note, after reading that article earlier and then reading about the plan for a 2,700-mile undersea power cable from Australia to Asia [paywalled] my first thought was do they know how often undersea cables break? There’s a whole new set of challenges in repair, though I suppose the same level of optical precision isn’t required. Also made me wonder about the effects on the surrounding environment/wildlife from the induced magnetic field.

1 Like

I can guarantee it.

I remember a TV show several years ago where the plot device for the episode was that the bad guy tapped a transatlantic fiber, inserting a few-millisecond delay, so that his company could react to market events faster than other high-frequency traders.

I asked a friend, who works for a major telecom company about this. He said that they would instantly notice the delay and fail-over the cable to a backup. They’re constantly running performance monitoring and someone would want to know how the cable suddenly got hundreds of feet longer.

Not to mention that you can’t tap a fiber without at least a momentary signal interruption. That will be logged and investigated. If it’s a high security fiber, that momentary interruption will actually cause all data to immediately be halted until an inspection can take place.

Now I remember, this was an episode of Elementary and was actually a decent plot device

1 Like

If you intercept everything how does the routing around work?

(Interesting article here: The Creepy, Long-Standing Practice of Undersea Cable Tapping - The Atlantic )

1 Like

You can’t intercept everything. The Internet generates orders of magnitude more data than even the biggest government can hope to monitor.

But if someone is splicing into a fiber or a bundle of fibers, this can be detected and service providers can update their routing tables to send traffic over other fibers.

Of course, governments don’t go physically tapping fibers. The just go to the network operators and tell them to shunt a copy of the traffic-of-interest from the routers to collection devices.

The buzzword for this is lawful intercept and all manufacturers of large switching equipment support it.

Of course, how much of the interception is actually lawful (and how many of those laws are Constitutional or justifiable) is a separate discussion, which is probably inappropriate for this forum, and definitely inappropriate for this thread.


The electromagnetic and mechanical effects of undersea power cables on local sea life has been raised as a possible major issue for offshore wind power generators. The people who harvest bottom-dwelling fish, shellfish, and lobsters in Maine are very concerned.

The plan for a 2,700 mile power cable from Australia to Singapore hasn’t died, but it should have. One of the major investors pulled out, but the company seems to have been bought by one of the other investors. I can’t see Singapore taking a significant amount of power from an undersea cable. There is also the problem that the peak power supplied would be in the afternoon, when Singapore can have their own systems. I’m in Australia, and have a relative who works in renewables research, and his opinion is that there are a lot of projects that are not properly thought through. Unfortunately, he can’t tell me which ones.