Found the following on the interwebs on the origins of gravlax. Today it is made differently:
The origin of gravlax can be traced all the way back to 14th-century North-Sweden. In the Middle-Ages, salt was expensive and most foods had to be preserved using alternative methods. In North-Sweden, peasants and fishermen developed a unique technique called gravad lax (“buried salmon” hence the name gravlax): The filleted salmon was placed in a hole in the earth, covered with birch bark and laid in a bath of water, the fish’s own blood and various spices and herbs. The result was a rather strong-smelling product that would be closer to todays infamous surströmming (fermented herring) than the gravlax that is eaten nowadays.
Well, thank you kindly. I learned something today. I figured your allusion to “buried” was, well, nuts, so I did a quick look only.
A little knowledge is a dangerous thing, I need to remember.
Have a good one!