Jotham, from Ultima V: Lazarus
After speaking with Jennifer in Ultima V, the Avatar spoke with Jotham. Jotham had seen many things on his travels, and spoke of the great whirlpools on the ocean. He told the Avatar of the rumor that collapses inside the Underworld had caused the whirlpools, and that a ship dragged into one would be spat out into the underground caves. He added that the rumor says that those who survive that journey are eaten by the horrible creatures living down there.
Ultima V: LazarusEdit
In Ultima V: Lazarus, Jotham told more information about his travels to the Avatar. In one of his travels, he and his crew found the Serpent Pillars. However, frightened by the stone serpents, they were able to steer their ship clear of the pillars, and so they never found out what would have happened if they had crossed them.