A Modern Swelkie

Among all the devices being tried out in the waters around Orkney to harness the energy of tides and waves, one caught my eye in particular. It's an undersea turbine, described as a 6m wide 'fan', and it is being tried out in the 'Fall of Warness' off the coast of Eday. I caught sight of it in a news item on the BBC the other day. Because the BBC report implied it was being tried out in the Pentland Firth, it reminded me of an Old Norse legend, a version of the widespread aetiological tale in which an undersea salt mill is said to be the reason why the sea is salt. One version of this tale attaches this legend to the Swelkie (sometimes written Swilkie or Swelchie), a fearsome tidal whirlpool in the Pentland Firth (I've discussed this a bit in this paper from the Durham Saga-Conference and also in one from the Uppsala Saga-Conference, which can be downloaded here). This picture of the turbine looks just like how I imagined the salt-mill...