If someone wanted to cause real harm to the infrastructure and they knew about the infrastructure.

They wouldn’t have taken out a few transformers that could be easily rectified.

They would have used a boat and dragged an anchor across the bay.

How large of a boat would you need to really do damage though? I suspect that most undersea cables are tough enough to withstand your average sub-1000HP fishing/water skiing boat, and would need something a bit harder to come by to be easily damaged.

You would need a rather large ship and anchor for that. The small boats that most people have access to wouldn't do much.

I'm not going to speak to specifics. Let's just say, you'd be surprised. It's more about the cutting force than it is say about the mass. Yes, a large boat will make even the dullest anchor a strong knife via force. But a small anchor that is sharpened could do the trick.

You don't need to split the wire in half. You merely need to expose it enough to cause it to go to ground with a significant enough amount.

The facility in question could see any boat on the water, and if a boat stayed over the lines too long. Authorities would have to be notified. After I left this exact thing happened by accident, and it was in an area where large boats did not enter due to the water being too shallow.

Take out the WTC with an airplane? You would need a rather large plane for that. The small planes most people have access to wouldn't do much.

Presumably a boat large enough to do that would also be able to be identified in the post match analysis too.

As someone who doesn't live in the Bay Area, I'm assuming there are cables of some sort that cross the bay?

The [Trans Bay Cable](https://en.wikipedia.org/wiki/Trans_Bay_Cable) is a 53mi-long cable carrying 400MW at 200kV DC (so that's 2000A). It's capable of supplying 40% of San Francisco's electricity needs.

According to [this web-page](https://www.researchgate.net/figure/Overview-of-the-Trans-Ba...), the cable is 10 inches in diameter, and [according to this briefing](http://www.caiso.com/Documents/070418_BriefingonTransBayCabl...) there's an inch-thick armour layer over another 2 inches of lead (wat?!) and PE. According to that same briefing, the cable seems to not be buried and is instead just layed directly onto the sea-bed.

So dragging an anchor probably would do more damage to your boat and the anchor than the cable itself - but I imagine a diamond-tipped cutting blade could probably make its way through the armor layer eventually - perhaps some carefully placed underwater explosives would help weaken it too. Just hope you have protection against the extreme current going through the cable travelling up your anchor...

So yes, it's within the realm of possibility for an individual to sabotage the SF Bay Area's electrical power system.

...that's scary.

But the thing about disrupting public utility infrastructure is that it doesn't fill people with fear - it just inconveniences them. If there was a news headline about some incel/qanon idiot dropping underwater explosives into the bay around this cable from a rowboat to shut-down SF's power supply it just seems... underwhelming and non-threatening: quite the opposite of a macho-masculine power-fantasy - and they'd probably get laughed out of the communities they claim to represent.

Explosives could easily cut right through it. You can cut cleanly through reinforced concrete bridge pillars with just high yield detonation cord or c4 collar charges.

The world of infrastructure security is quite terrifying once you start digging into it. I believe at some point in the 1970s, the CIA started doing red team operations on domestic terrorism infrastructure vulnerabilities. They eventually stopped or slowed significantly because they had so many simulated breaches that they couldn't possibly contain them all. They had to significantly refocus their attention on prevention by identifying who/what/where/why instead of how (their traditional cold war methodology that many thought was outdated), because there were practically infinite ways identified that infrastructure could be crippled.

No need for explosives even. The technology for quickly cutting through reinforced concrete has been available since the end of the nineteenth century, and has been an industrial thing since at least the middle of the twentieth century.

But does that technology work well underwater - and can it be implemented and/or used by an individual non-expert?

Sorry, I'd been thinking bridge pillars.

For underwater cables I wouldn't say non-expert: the trade that has the expertise generally pays around USD 60k per annum.

Being around 2 kA discharges underwater is probably not a great idea, however. Automation would be one possibility, raising required expertise and lower required headcount. A little searching indicates that if one is willing to acquire a ROV, there are at least two other commercially available cutting technologies, both of which are normally used for much larger cuts than a 20 cm cable bundle.

Much modern infrastructure relies on people not being jerks, but then again, modern society also relies on people not running around shooting each other, which seems to work.

(except when it doesn't: this is why I am looking into Yugoslavia now. How does one get from socialist brotherhood to shooting each other? I have colleagues, yugo refugees, whose conspiracy theory is that the conflict was externally stoked, but I currently find people being stupid to be a more parsimonious explanation.)