Duane W. Roller (1946- ) is an American archaeologist, author and professor emeritus of classics, Greek and Latin at the Ohio State University. Among his many published works is Through the Pillars of Herakles  in which offers a new review of the early Greek and Roman exploration beyond the Mediterranean. The book was briefly reviewed in the New Yorker(a).
In Through the Pillars of Herakles [p.203], he states that “The exact location of the Pillars of Herakles was long a matter of dispute. Although they may seem obvious today as the two large mountains at the western end of the Mediterranean, Gibraltar and Jebel Mousa, such was not the case in antiquity, and understanding of the region changed as topographical knowledge increased. At some early date, Homer’s mythical and unlocated Pillars of Atlas (Od. 1.51-4) became associated with the wanderer Herakles, but as the western end of the Mediterranean became better understood in the latter seventh century BC, uncertainty increased rather than decreased. Herodotus, who mentioned the Pillars several times, placed them east of Gadeira and Tartessos (4.8, 152), which could mean anywhere in the 50-kilometre-long strait (the modern Strait of Gibraltar) that runs east to the opening of the Mediterranean, through rugged topography with several promontories that could be identified as the Pillars, although especially prominent are Gibraltar and Jebel Mousa (the Kalpe and Abilyx of Strabo) at the eastern end. The early prominence of Gadeira caused some (such as Pindar) to place them in that area, or at points, east thereof, such as Tarifa or Cape Trafalgar: the sources seem uncertain as to whether height or prominence was the defining criterion.”
In an article in the Oxford Classical Dictionary, Roller noted that the name “Atlantic” (Greek Atlantikos or Atlantis) is not documented as applying to the ocean west of the inhabited world until the 5th century BC.
Xaverio Ballester is a Spanish linguist and a professor at the University of Valencia. He is a leading proponent of Paleolithic Continuity Paradigm or PCP), which suggests that the Proto-Indo-European language (PIE) can be traced back to the Upper Paleolithic, several millennia earlier than the Chalcolithic or at the most Neolithic estimates in other scenarios of Proto-Indo-European origins.(a)
He has written on the subject of Atlantis in a paper on the Academia.edu website(b). He discusses the Pillars of Heracles at some length noting that “it is also hardly credible that for the distant Greek world the expression arose precisely from the reference to a strait, that of Gibraltar, which the Greeks must not have known more or less directly, at the earliest, until the end of the 2nd millennium BC, a time that must also be well after the emergence of traditions about Heracles. The corollary of all this is the inevitable suspicion that other older Heracles columns, perhaps the original ones, must have stood much closer to Athens, much closer to Greece.”
He suggests the Dardanelles as the possible location of the Pillars, with Atlantis in Anatolia along with the perimeter of the Black Sea.
Alexander Knörr is the author of Hagar Qim  in which he discusses the cart-ruts of Malta, concluding that they must be at least 9,000 years old. But he goes further, declaring that the famous temples of Malta are more than 12,000 years old!
>Knörr has published, in German, a wide selection of both fiction and non-fiction books(b).< Inevitably, he tackles Atlantis, attributing its demise to the breaching of a dam at Gibraltar leaving Atlantis at the bottom of the Mediterranean.>However he offers little evidence to support his wild speculations.<
Nevertheless, Roland M. Horn has offered a favourable review of Knörr’s book(a).
(b) https://www-amazon-de.translate.goog/kindle-dbs/entity/author/B00H1T3HBM?_encoding=UTF8&offset=0&pageSize=12&searchAlias=stripbooks&sort=author-sidecar-rank&page=2&langFilter=default&_x_tr_sl=de&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=sc#formatSelectorHeader *
Alexander M. Gorodnitsky (1933- ) is a member of the Russian Academy of Sciences, who is a geologist and oceanographer by profession(a). His other interests range from ancient civilisations to music composition. The former led him to conclude that Atlantis had existed and was situated between Gibraltar and the Azores near, the Ampere and Josephine seamounts.>Paulo Riven also favoured the Josephine/Torre seamount region holding the location of Atlantis(b).<
Landbridges,>in biogeography, are described by Wikipedia as “an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and colonize new lands. A land bridge can be created by marine regression, in which sea levels fall, exposing shallow, previously submerged sections of continental shelf; or when new land is created by plate tectonics; or occasionally when the sea floor rises due to post-glacial rebound after an ice age.”<
In the distant past, landbridges are believed to have played a critical part in early human migration. Similarly, landbridges, both real and speculative are important components in many Atlantis theories. There is no doubt that the ending of the last Ice Age and the consequent rising sea levels led to the creation of islands where continuous land has previously existed. The separation of Ireland and Britain from each other and from mainland Europe is just one example, the latter leading to a number of writers identifying ‘Doggerland‘, which lay between Britain and Denmark as the home of Atlantis.
The two most discussed landbridges were at the Bering Strait, where it is thought that it provided the gateway for humans to enter the Americas from Asia and an Atlantic landbridge, which was proposed as early as the 17th century and later by John B. Newman in 1849 [488.8], who wrote that “in former times an island of enormous dimensions, named Atlantis, stretched from the north-western coast of Africa across the Atlantic ocean and that over this continental tract both man and beast migrated westward.“
The Atlantic landbridge idea became quite popular by the end of the 19th and beginning of the 20th centuries and even as late as the 1970s when espoused by Rene Malaise(a), but is now completely abandoned.>Ignatius Donnelly referred to such a landbridge as a ‘connecting plateau’ linking Europe, Africa and America that allowed plants and animals to cross in both directions.<
Although there was only one suggestion that the Bering Strait was in any way connected with Plato’s Atlantis, several commentators identified an Atlantic landbridge as the ideal location for Plato’s Atlantis, particularly as he placed it in the Atlantic Sea. However, this should not be confused with the Atlantic Ocean, a word that had an entirely different meaning for the ancient Greeks.
The idea was initially put forward in order to explain the floral and faunal similarities shared by the Old World and the New World of the Americas. The hypothetical Atlantic landbridges or a series of steppingstone islands. also offered possible routes for the peopling of the Americas by Europeans and/or Africans. It was not long before the discovery of the Mid-Atlantic Ridge(b) seemed to confirm this idea. Then it was suggested that Atlantis existed on this landbridge, which was destroyed by rising sea levels after the last Ice Age, leaving just the Azores, Madeira and a few other islands as remnants.
A number of landbridges have been proposed for the Mediterranean and linked to a variety of Atlantis theories, the most notable being proposed for the straits of Gibraltar, Sicily, Messina and Bonifacio. Although it is evident that landbridges existed at most of these locations, to associate them with any particular Atlantis theory requires that the date of their existence is compatible with Plato’s narrative.
(a) Atlantis, Vol.27, No.1, Jan-Feb 1974.
The Bell Beaker People identified by their distinctive pottery existed from around 2800 BC until 1800 BC. They occupied large areas of Iberia, Central Europe and the British Isles as well as some of the western Mediterranean islands. Melville Nicholls claims that they originated in Portugal. Associated with them are the Wessex people divided into Wessex I and Wessex II, who are found in western Europe and southern Britain, the latter, dated to 1650-1400, were involved with the construction of the later stages of Stonehenge.
Uwe Topper associates the beginning of metallurgy with the Bell-Beaker People(e).
Nicholls and others(b) have linked Atlantis with the Bell Beaker culture, identifying a location near Gibraltar as the site of Atlantis. He published his views in Children of the Sea God, a 2013 Kindle ebook(a) and a second ebook, The Real and Imaginary Atlantis generally reprising the first, later the same year! Further comment from Nicholls can be found on an internet forum(f).
David D. Miner, is an American Doctor of Medicine, who published a paper linking the Beaker People, Atlantis and Salisbury Plain. He makes a serious and imaginative effort to explain details in Plato’s narrative in the context of this proposed association.
The Beaker People are also claimed to have crossed the Atlantic, where they have been linked to the Adena culture of North America. A leading exponent of this theory is undoubtedly Jay S. Wakefield, co-author of How the SunGod reached America . He has reprised his views in a 2018 paper on the Diffusion & Migration website(c)(g) . Others have expanded on his concepts(d).
(b) https://widespreadblyss.blogspot.ie/2013/02/platos-atlantis-and-bell-beaker-culture.html (link broken Sept. 2018)
Carl Festin (1957- ) is a Swedish researcher who was prompted by questions from his children to investigate the history of civilisation. His studies led him to conclude that the hundreds of worldwide flood myths involved a catastrophe that involved the biblical story of Noah* and Plato’s tale of Atlantis.
In a PowerPoint presentation provocatively entitled Noah, Refugee from Atlantis Festin outlines a new Atlantis theory. He first suggests that a ridge of sediment built up in the vicinity of Gibraltar gradually cutting off the Mediterranean from the Atlantic when sea levels were much lower during the last Ice Age. This similar in some ways with the theory of Paulino Zamarro.
Festin posits an island in the Eastern Mediterranean, south of Crete, called Basileia, which dominated land around what we now call the Ionian Sea. This nation was known as Atlantis.
He identifies the mountains of what is now Crete and Al Jabal Al Akhdar (Green Mountain) in Libya as the Pillars of Heracles. These are shown on a new map(b). Other maps(c) show his proposed Atlantean capital, Poseidopolis and are sometimes oriented east-west.
Around 3,500 BC the Gibraltar ridge broke due to the pressure of the rising ocean levels following the melting of the ice. The influx of cold water into the Western Mediterranean Basin created extensive anti-cyclonic rainfall over Basileia (40 days and nights!). The Western and Eastern Mediterranean Basins were separated by a landbridge at the Strait of Sicily which now broke, inundating the eastern basin. Festin claims that the millions of tons of additional water created earthquakes in seismically fragile central Mediterranean, destroying Basileia. Survivors included Noah who headed eastward. Others reached both North and South America.
Festin is now organising a five day cruise in the Mediterranean, which will include a dive in a small submersible to the Atlantean capital Poseidopolis on the submerged island of Basileia lying between Crete and Cyrenaica in Libya. The adventure can be watched on board the ship on large screens, while for the really enthusiastic, there are 8/10 spaces available in the submarine. He currently estimates the basic cost to be €2,000 and €100,000 for each of the 8/10 submariners(d). I think comment is unnecessary!
His theories are published in Swedish as Flykting från Atlantis (Refugees from Atlantis)(a).
Atlantrope in spite of its name has no connection with Atlantis. It was in fact the name of an enormous dam building project first proposed in 1928 by the German architect Herman Sörgel (1885-1952). Ironically, he was hoping to create artificially what some think had existed in reality and within the memory of man and whose destruction may have led to the destruction of Atlantis.
His idea was to create dams at Gibraltar, the Dardanelles and the Strait of Sicily and gradually reclaim land by lowering the level of the Mediterranean and incorporate hydro-electric plants into the scheme(a)(b). He went further and suggested flooding large sections of the Sahara Desert. For a few years after Sörgel’s death, efforts were still being made to gain support for the idea.
>In 1997, Robert G. Johnson, a retired professor, also proposed the damming of the Mediterranean at Gibraltar(c).<
Sörgel’s proposal was briefly referred to in SKY TV’s second series of The Man in the High Castle.
Strabo (c. 64 BC – 23 AD) was an important Greek geographer and historian who wrote (i) of his full agreement with Plato’s assertion that Atlantis was fact rather than fiction. An English translation of his Geography (Geographica) in three volumes can be read online .
The location of the Pillars of Heracles, mentioned by Plato, is assumed by many to have always been situated near the Strait of Gibraltar. Other researchers have claimed that this was not the only location and have referred to various classical writers to support this contention, one of whom was Strabo, who records (ii) the variety of opinions regarding the location of the Pillars of Heracles among classical writers, adding that Alexander the Great on reaching the easternmost point in his military campaign erected an altar with ‘Pillars of Heracles’, giving further support to the view that the ‘Pillars’ were not a singular landmark but a feature that was to be found at different locations at different points in history. Strabo produced a map of Europe on which he located the ‘Pillars’ at Gibraltar in his day (1st century AD). Strabo also noted that, in the distant past 300 cities lined the coasts on either side of the Pillars.
Strabo also wrote (iii) of Hera’s Island as being one of two islands located near the Pillars of Heracles, beyond which was Gades in Spain. The two islands have not been identified. He was writing some centuries after Erathostenes had been the first to place the ‘Pillars’ at the western end of the Mediterranean.
James Bramwell has cast some doubt on the reliability of ancient geographers in general and Strabo in particular, whom he claims[195.129] oriented the Pyrenees as running north-south rather than their actual east-west.>Nevertheless, Strabo’s reputation would appear to have been enhanced by the discovery a few years ago that Piraeus, a small peninsula near Athens had been an island around 6,000 years earlier. Over time, sedimentary deposits had gradually built into an isthmus joining the island to the mainland. Strabo had recorded the earlier island status of Piraeus two thousand years ago, millennia after the event and unconfirmed until now(a).<
I should mention that, coincidentally, a temple of Hera was discovered near Marsaxlokk on Malta, the larger of the two principal Maltese islands.
(i) Geographia (2.3.6/7)
(ii) Geographia (3.5.5)
(iii) Geographia (3.5.3)