I just responded at some length to this then clicked the "Best Answer" button before saving it, and my comments disappeared.
First, thank you for taking so much trouble with this. The links are extraordinary and I'd never heard any of the songs, so they were all new.
All your links were interesting. I usually avoid Wikipedia but those were worth reading.
I actually wondered whether the Triangle and the Sargasso Sea were parts of the same phenomenon and now, thanks to you, I know. What an amazing man Himilco must have been if he actually reached the Sargasso Sea 2400 years ago. It's more likely that he was exaggerating the difficulties of his voyage, but his account of the seaweed was right on the money.
I've read Plato's account of Atlantis. If I remember correctly he was recounting a tale told to him by travellers. Much more believable is Dr Charles Pellegrino's account in "Unearthing Atlantis" in which he postulates that a more advanced (by a couple of centuries) civilisation existed on the Greek Island of Thera. It didn't sink into the sea but was destroyed in a single day by a volcanic eruption whose properties were not understood until the eruption of Mount St. Helens (WA) in 1980.
Again thanks for taking so much trouble with your answer.