[toomuchtodo]

Absolutely, boils down to your threat model. If you are defending against a nation state actor, you are probably going to want to deploy underwater surveillance across the cable's length and station folks who can respond when someone nefarious shows up to chop chop. No security is absolute, you are either dissuading or slowing down an attacker based on their resources and available window of time. It's 42 miles/67km from Finland to Estonia across the Gulf of Finland, which does not seem challenging to defend vs cables crossing oceans. Sweden to Estonia is definitely a bit further.

Finland and Estonia share a 1GW electrical interconnector (composed of two HVDC submarine cables, with a signed MOA for a third) Estonia is using to consume power from Finland's recently turned up nuclear generator. I am unaware if it is buried, but it is a strategic critical infra asset that likely requires defense.

Its easy to overthink these problem spaces (imho), but I propose that Russia's current geopolitical posture adds an element of a wildcard necessitating the thought exercise. This infra can take months to build or repair, but only hours to cripple.

https://en.wikipedia.org/wiki/Estlink

https://app.electricitymaps.com/zone/EE?wind=false&solar=fal...

Example commercial system: https://electronica-submarina.com/protection-of-critical-inf...

Example US Navy military system SOSUS: https://en.wikipedia.org/wiki/SOSUS (which is suspected to be what detected the Titan submersible implosion)