Strange enough the Atlantis franchise of claims have branched out?
Here is some one claiming Atlantis is in Canada ( I WONDER IF THE OAK ISLAND GUYS HAVE NOT HEARD OF IT YET?)

Gotta be another season for the brothers with that hypothesis.
Atlantis in Canada
Even so not to be out done Bolivia is having a crack at the claim.
Atlantis in Bolivia
What I find interesting is "Diodorus Siculus refers to Atlantians still surviving in his day but apparently somewhere in the Americas"
Diodorus Siculus
Diodorus Siculus or Diodorus of Sicily was an ancient Greek historian. He is known for writing the monumental universal history Bibliotheca historica, much of which survives, between 60 and 30 BCE.
" The Americas

?" then if that was true knowledge of America was nearly 1500 years before Columbus?
Bibliotheca historica (Ancient Greek: Βιβλιοθήκη ἱστορική, "Historical Library") is a work of universal history by Diodorus Siculus. It consisted of forty books, which were divided into three sections. The first six books are geographical in theme, and describe the history and culture of Egypt (book I), of Mesopotamia, India, Scythia, and Arabia (II), of North Africa (III), and of Greece and Europe (IV–VI). In the next section (books VII–XVII), he recounts the history of the world starting with the Trojan War, down to the death of Alexander the Great. The last section (books XVII to the end) concern the historical events from the successors of Alexander down to either 60 BC or the beginning of Caesar's Gallic War in 59 BC. (The end has been lost, so it is unclear whether Diodorus reached the beginning of the Gallic War, as he promised at the beginning of his work, or, as evidence suggests, old and tired from his labors he stopped short at 60 BC.) He selected the name "Bibliotheca" in acknowledgement that he was assembling a composite work from many sources. Of the authors he drew from, some who have been identified include: Hecataeus of Abdera, Ctesias of Cnidus, Ephorus, Theopompus, Hieronymus of Cardia, Duris of Samos, Diyllus, Philistus, Timaeus, Polybius and Posidonius.
Diodorus' immense work has not survived intact; only the first five books and books 11 through 20 remain. The rest exists only in fragments preserved in Photius and the excerpts of Constantine Porphyrogenitus.
While I am sure he took much information from the writings of Timaeus? Yet I can see no reference to Americas in Timaeus?
The first known reference to "Americas" was on 1507 map.
The Waldseemüller map or Universalis Cosmographia ("Universal Cosmography") is a printed wall map of the world by German cartographer Martin Waldseemüller, originally published in April 1507. It is known as the first map to use the name "America". The name America is placed on what is now called South America on the main map. As explained in Cosmographiae Introductio, the name was bestowed in honor of the Italian Amerigo Vespucci.
The map is drafted on a modification of Ptolemy's second projection, expanded to accommodate the Americas and the high latitudes. A single copy of the map survives, presently housed at the Library of Congress in Washington, D.C. But as far I can see there is no mention of Americas?
Waldseemüller also created globe gores, printed maps designed to be cut out and pasted onto spheres to form globes of the Earth. The wall map, and his globe gores of the same date, depict the American continents in two pieces. These depictions differ from the small inset map in the top border of the wall map, which shows the two American continents joined by an isthmus.
If there is a real historic document mentioning the America whose publication was long before predating 1507 that would be an amazing discovery in itself? However I have my doubts as modern translations can have things added in translation. Some times intentionally and some times un intentionally.
The world map from the Seven Days of Geography (Septe Giornate della Geographia), an Italian terza rima paraphrase of Ptolemy's Geography. After Ptolemy's second projection. Shows no sign of the Term "Americas"
The Ptolemy world map is a map of the world known to Hellenistic society in the 2nd century. It is based on the description contained in Ptolemy's book Geography, written c. 150. Based on an inscription in several of the earliest surviving manuscripts, it is traditionally credited to Agathodaemon of Alexandria.
Kanacki