I asked this question to a class of smart 18-19 yo college students a few years ago. Almost everyone thought it was done with some kind of wireless transmission (e.g. "by satellite"). The idea that it was physical cables lying in the mud of the sea bed was a revelation.

Did they speculate about how it was done before fiber optics?

I'm sure that Marcono would like their answer as well.

I’ve met quite a few non technical people who assume the Internet is carried by satellite.

I distinctly remember "learning" this in K12, before getting deeper into the technology industry. One of our textbooks had a diagram with lines showing signals flowing from continent to satellite to continent. It wasn't until I got deeper into the industry that I learned satellite latency is awful, bandwidth is limited, and everyone uses cables or microwave point-to-point links when they can. (Actually, the role of those point-to-point links is drastically undersold for how ubiquitous they are in our cities. Worked with some Ubiquiti gear professionally once, and now notice them everywhere).

It's actually a very reasonable assumption, as most people don't really know about the limits of fiber, but they do own mobile phones which seem to work almost wherever they are thanks to wireless technology.

"Normal" people don't know that kinda stuff.. Let's be honest, they make many of their assumptions from TV and Movies - and often those disaster movies focus on the world grinding to a halt because "the satellite network is down" (I do the same with other industries!)

And the delay

Depends where you are located... e.g. for cook islands this is the reality till they also get their own fibre optics in mid 2020.

that was my own assumption until I learned about the under sea cables.