Many cultures share legends of the drowning of rivals, or those who would not convert to the ideology du jour, seers and magicians seen as threats to the power of this or that king, or the innocent so as to appease the gods. At Bukkoy, there are under-surface rocks used for that purpose in ages past. These are skerries, little rock-islands, where stories of vindictive or punitive drownings surround. It is said, for example, that Olaf Tryggvason and others chained indigenous religious, the warlocks, the supposed magicians, the sorcerers, to the skerry off the farm manor on Bukkoy, perhaps here. That would teach them that resistance to conversion to Christianity did not pay. There they would drown as their noses fell below the rising tide. See http://theonomyresources.blogspot.com/2014/01/olaf-tryggvason-christian-viking-king.html/
Olaf Tryggvason was the killer-mutilator of those who would not convert to his form of Christianity (form an army and conquer). Research the tortured Eyvind Kinnrifi, and Oliver the Martyr, and Guthroth whose tongue was yanked out, see Pagan Memory Calendar at http://www.giornopaganomemoria.it/calendar.html, is rosy in later years. In later centuries Olaf T. is revered and airbrushed as the one who simply drove pagans out.
Out? Not really. They keep many traditions, as the conquered often do, under the radar. Still believe in trolls? Of course we do. Hush, child. Bar the door. February 9 comes each year, and we remember. See http://www.examiner.com/article/day-of-remembrance-for-eyvind-kinnrifi-on-february-9th
Olaf T. himself leaped into a fjord when losing a battle, and drowned, although sightings continued.
The fervor of newly Christianized kings is traceable to the unyielding demands of the new institutional church, that cast all aspects of indigenous religious society as superstition and work of the devil.
The new church hierarchy frowned upon women's autonomy, including their going to war, and stamped out reverence for the clairvoyance talent so many demonstrated (especially among the Germanic tribes, where that aspect was seen as sacred). That power challenged the precepts of the church itself. These qualities of some women, for wisdom, foreshadowing, had led to a higher status for women in Scandinavia, especially Norway, than in the southern European cultures, is that so? See http://www.visithaugesund.no/Haugalandet/Viking%20women%20text.pdf/. It is logical, then, that legends about women casting spells would grow and lead to their also being chained off Bukkoy to welcome the tide for having tried to cast a spell on the king.