We were lucky on the ship. We had just turned around the Lofoten Islands from Tromso to Narvik. The officer of the watch made the usual announcement through the TV etc that the lights were visible, so we wrapped up and headed up to the deck are in front of the gym. It was heaving with pax, but was a good show. This subsided and most went back inside somewhere, but a handful of us stayed out to see if it returned. Right place at the right time, it just erupted overhead of the ship followed by a hasty rushed announcement basically saying get outside quick, you do not want to miss this.
As you say, magical. Bucket list item ticked off, and never to be forgotten.