Re: What is really upsetting about the pipelines.
They can scout the location days ahead. Drop camera, radar, drone, you name it, to acquire exact point of attack. Get gps locations and depths ahead. Prepare proper equipment and explosive devices.
They can even drop an anchor with strong cable & attach floating marker, maybe signal emitting marker, for quick access on the day of operation.
When the time come, find the marker with gps location. The cable is a secure way to send bombs down to the pipe at bottom.