Isn’t it millons of teeny tiny reconnections?
In: Engineering
Nope.
A single fiber can carry absolutely absurd amounts of data across. Undersea cables carry fibers measured in dozens, not hundreds.
The new MARAE cable between Virginia and Spain for example carries 224 tbps of data on a single digit number of fiber pairs. 8 pairs to be exact.
Which one? [There are a lot of undersea cables](https://www.submarinecablemap.com/), and each one is designed to last at least 25 years. Old ones can get pulled up, but they’re usually just left on the ocean floor. There are some companies that will try to acquire the salvage right to them and pull them up for raw material recycling, but most of those materials get sold back to the companies that made the cables in the first place and re-used into new ones. Modern cables have diagnostics built in so whenever one starts having troubles they can tell where and replace just the malfunctioning segment instead of writing the whole cable off and laying a new one.
In addition to what everyone else says, the most common way to fix stuff deep underwater (That you can’t just pull up to the surface) is called saturation diving. Depending on the job, people will stay and live in pressurized compartments down there, for looong periods of time. Weeks, possibly months. They don’t go below 1,000 feet as often, but have gone as deep as 2,300 feet. Look up a youtube video on it, it’s neat.
Didn’t they just replace some major ones in Red Sea? I’m trying imagining splice and replace section and it just seems absurd
Here’s a great (long, but worth it) article on repair of underwater fiber optic cables: [https://www.theverge.com/c/24070570/internet-cables-undersea-deep-repair-ships](https://www.theverge.com/c/24070570/internet-cables-undersea-deep-repair-ships)
There’s a fairly nice story about this they used to teach us about the importance of line impedence
” At the time, undersea cables were unreliable. It was not uncommon for the signal on a cable to fade and then die completely, most often due to a short circuit caused by failure of the [gutta-percha](https://en.wikipedia.org/wiki/Gutta-percha) insulation between the copper conductor and the iron sheath surrounding it. When a cable failed, there was no alternative but to send out a ship which would find the cable with a grappling hook, haul it up to the surface, cut it, and test whether the short was to the east or west of the ship’s position (the cable would work in the good direction but fail in that containing the short. Then the cable would be re-spliced, dropped back to the bottom, and the ship would set off in the direction of the short to repeat the exercise over and over until, by a process similar to [binary search](https://en.wikipedia.org/wiki/Binary_search_algorithm), the location of the fault was narrowed down and that section of the cable replaced. This was time consuming and potentially hazardous given the North Sea’s propensity for storms, and while the cable remained out of service it made no money for the telegraph company.
Heaviside, who continued his self-study and frequented the library when not at work, realised that knowing the resistance and length of the functioning cable, which could be easily measured, it would be possible to estimate the location of the short simply by measuring the resistance of the cable from each end after the short appeared. He was able to cancel out the resistance of the fault, creating a quadratic equation which could be solved for its location. The first time he applied this technique his bosses were sceptical, but when the ship was sent out to the location he predicted, 114 miles from the English coast, they quickly found the short circuit.”
[https://www.fourmilab.ch/fourmilog/archives/2018-11/001795.html](https://www.fourmilab.ch/fourmilog/archives/2018-11/001795.html)
This long [article](https://www.wired.com/1996/12/ffglass/) by Neal Stephenson in Wired Magazine will tell you everything there is to know about it.
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