Maybe the Shadowy Seas were haunted by dead swan ships
Completely stupid headcanon
I saw the headcanon that Teleri elves’ ships were sentient like Anglachel and I absolutely love it
If Teleri elves’ ships were sentient then they probably turned into something else after they got destroyed
The ones that sank turned into the enchanted isles
The ones that were burnt into ashes and smoke turned into the shadows and mist
The isles, shadows and mist moved just like the way they were when they were still ships
Teleri could walk on the islands and sail in the shadows & mist safely but anyone else (Especially Noldor) got knocked out in very ungentle way
The isles and mist disappeared in the end because their makers finally managed to convince them that it’s safe to be ships again
One of the first things every Teleri elves died in first kinslaying did after reembodiment was to find the isle/piece of shadow or fog that was their destroyed ship.
(The isles and shadows and fog looked all similar but somehow the elves could just tell. Creator’s instinct, something like that.)
It took a long while, but slowly they rebuilt the ships and coaxed the spirits back into their new bodies
(The ones that got burnt were the most traumatized.)
(Some ship spirits had opinions on what exact kind of new body they wanted. Some wanted to be shaped like seagulls or geese or killer whales.)
(Most of them wanted fire proof coating and some mechanisms that allowed them to shake down evil abductors and auto-pilot to safety.)
When Host of the West went to fight in Beleriand some of the ships they took were new ones with old spirits.
People had to carefully group the Noldor elves with Teleri & Vanyar elves and make sure the Noldor stay far away from the edges of deck. Otherwise they kept getting shook into the sea.
(My cracky theory “in Arda everything that existed for a long while or carried a lot of emotions and thoughts eventually started to develop some kind of spirit”)