Also worth noting that even if you put them underground, you could flood your tunnels, or have an earthquake, or a giant rabid mole attack, etc...
I don't read your comment as ignoring this, but I want to point out for everyone that reliability always has tradeoffs about what events you want to be able to handle and how much preparation you want to do / pay someone to do for you.
Our (german) underground cables are waterproof and bite-proof, the latter to varying degrees.
Earthquakes are an issue, but iirc they only tend to require a few splices, not a new cable.
I don't read your comment as ignoring this, but I want to point out for everyone that reliability always has tradeoffs about what events you want to be able to handle and how much preparation you want to do / pay someone to do for you.