Hallimor

There was a time when fishermen would venture out into the wider rough seas away from the mainland on boats to catch fish on behalf of the lightning clans. On one sailing trip past the shifting expanse near the southern icefields, a particularly unusual weather had befell them. Once cold rough seas had become like smooth glimmering glass, and a thick mist enveloped. The sky turned to night, dark but full of stars, light only a gloom through the haze.
Underneath what seamed like a swathe of flowing dark sinister forms and faces writhed in the deep.

Enamored, the fishermen watch, staring down the sides of their boat watching the ever creeping wonder. Distantly in the barely seeable thick mist, an ear-splitting scream ruptured from someone unseeable. The mist burst into rain and storm. Instant waves as high as mountains surged, dwarfing the boat and the hopeless sailor souls, now lost beneath the waves to mingle with the serpent beasts below.

Soon, from the tides to land, an island not seen. The fishermen sailors reawoke in a haze, minds lost and bodies changed. They are the Sirens of the lost, calling the names of others lost to join them.