The word gravlax comes from the Northern Germanic word gräva/grave ('to dig'; modern sense 'to cure (fish)') which goes back to the Proto-Germanic *grabą, *grabō ('hole in the ground; ditch, trench; grave') and the Indo-European root *gʰrebʰ- 'to dig, to scratch, to scrape',[3] and lax/laks, 'salmon'.

During the Middle Ages, gravlax was made by fishermen, who salted the salmon and lightly fermented it by burying it in the sand above the high-tide line.

Perhaps the oldest reference is found in 1348 in Diplomatarium Norvegicum [4] as the nickname of a man named Óláfr, who was a delegate in a salmon fishery.

Instead the salmon is "buried" in a dry marinade of salt, sugar, and dill, and cured for between twelve hours and a few days.

As the salmon cures, osmosis moves moisture out of the fish and into the salt and sugar, turning the dry mixture into a highly concentrated brine, which can be used in Scandinavian cooking as part of a sauce.