Here’s the situation - you need to plant hundreds of lbs (at least) of specially designed explosives to blow up a pipeline with 1.5 inches of steel and 4 inches of concrete. You will need sophisticated remote detonation switches. You have do to this work 100 meters underwater where the temperature in water about 40 Deg. Repeat this in 8 different spots of the pipeline.
To dive that deep, you need advanced training, TRIMIX gas, and you’ll probably only be able to work about 20% of the time, as the rest will be spent decompressing. So you’ll probably need a team of a dozen divers, or more, working over several days with a large surface support ship.
Oh - and don’t get detected either, ‘cause you will be working a few miles offshore from Denmark, and in the middle of NATO military operations
And neocon bullshitters expect people to buy the notion that some ad hoc gang of Russians and Ukrainians did this?
No, you don’t need any of that.
It does not need to be sophisticated explosive. Naval mines and torpedoes worked just fine with guncotton filler over a hundred years ago.
Ukraine has lots of that “sophisticated” stuff anyway, in its own stocks of Naval mines and torpedoes. They still have two Navy yards in Odessa and Mykolaiev.
You don’t need sophisticated detonation switches, just a timer.
Depth was @70meters
All the diving tech is commercial and common in that world.
Divers would only be needed to guide the lowering of the charges into position.
Ukraine has experienced commercial divers.
It would not have been an ad hoc gang, it would be a state supported operation.
And, no doubt, both NATO and Poland carefully looked the other way.