I think it's possible to build a platform, like an oil drilling platform, survivable in the middle of the ocean (against storms and rogue waves) and hook fiber

I think it's possible to build a platform, like an oil drilling platform, survivable in the middle of the ocean (against storms and rogue waves) and hook fiber into it by dropping fiber in extremely high-strength conduit (like oil drilling pipe) to the ocean floor and then across the ocean to continents. I don't think the cost/benefit is acceptable considering more serviceable locations that already have fiber, like Hawaii in the Pacific. Operational costs for a floating platform are much higher, and fixing anything major would take days instead of hours. What about DDoS attacks (N/A if these are private network links) or real pirate attacks?