In the first episode of this series, How it Works, we discuss the process of tunnel construction, what submarine cables are, and how they are laid on the ocean floor.
Sources:
https://science.howstuffworks.com/engineering/structural/build-underwater-tunnel.htm
https://wonderopolis.org/wonder/how-do-you-build-a-tunnel-underwater#:~:text=To%20use%20this%20method%2C%20builders,pump%20out%20any%20remaining%20water.
https://www.builderspace.com/how-are-underwater-tunnels-built-what-you-need-to-know
https://www2.telegeography.com/submarine-cable-faqs-frequently-asked-questions 5. https://www.datacenterdynamics.com/en/analysis/what-is-a-submarine-cable-subsea-fiber-explained/