Ok SOG, here's a brief list to get you started. I'll see what I can dig up on the Naacal and the continent of Mu (other than the brief blurb here) when I get more time.
1. Akrotiri (Ancient Thera);
Western civilisation has long been fascinated with the Ancient Greeks: a race who advanced art, science and mathematics at almost superhuman speed. But the Greeks weren’t the first highly-complex civilisation to arise in Europe. Just as modern Europe is in awe of people like Archimedes, Plato and Homer, so were the Greeks in awe of the Minoans.
Put simply, the Minoans were brilliant. Arising on Crete around 2,700 BC, they spread across the Aegean Sea, building towering palaces, three-storey buildings, cobbled roads and establishing Europe’s first drainage and water systems. While we were still living in huts, smashing each other across the head with flint axes, the Minoans had created a highly-sophisticated Empire that would span a thousand years…before collapsing in under fifty, following the overnight destruction of Akrotiri.
A small, unimportant trading port, Akrotiri had the misfortune of being at ground zero when the Thera volcano exploded, detonating with the force of four Krakatoa’s. The town was instantly swamped with ash. The blast triggered tsunamis that smashed Crete to pieces. Crops were destroyed, the sun blotted out and the entire Minoan civilisation reduced to ashes. In a single lifetime, an Empire that had lasted sixty generations fell into ruin and disappeared, its incredible achievements all but lost to history.
2. The Continent of Mu (Pacific Ocean):
Like Atlantis, Mu was said to be almost-frighteningly sophisticated. The whole of humanity was concentrated in its dozens of glittering cities, ruled over by a God-like ‘white race’ - an unfortunate indication of the time the myth arose in. With outposts in India, Central America, China and Egypt, the people of Mu influenced the development of all great civilisations, until their continent vanished at the dawn of history, devoured in a single night of fire and flooding. Fast forward to our modern times and there is precisely zero evidence that Mu ever existed. However, that hasn’t stopped the wishful few from bringing it up every time some new underwater landmass is unexpectedly discovered.
3. Ys (Brittany, France):
The legend of Ys is what happens when you collide the myth of Atlantis with Sodom and Gomorrah. Situated alongside modern Brittany in France, Ys was said to be a spectacular city-state, protected from the roaring sea by a complex dam system that kept the population from drowning at high tide. Built sometime between 1500 BC and the 5th century, it was allegedly also a deeply immoral place - a French Sodom that was wiped out when King Gradlon (a semi-historical figure) opened the dam in a fit of wrath and drowned the entire population. Although possibly thought to be historical fact many years ago, Ys is now known to be nothing but fiction: an interesting tale that’s been told for generations, and believed by no one.
4.
The Kingdom of Mohenjo Daro (Modern Pakistan):
There are some mysteries we, in all likelihood, will never know the answer to. The ancient city of Mohenjo Daro is one such mystery. Uncovered in modern-day Pakistan in 1911, it’s been dated from around 2,500 BC - 1,900 BC, and all evidence indicates it was stunningly advanced. There are no palaces, no temples or anything else suggesting an autocratic rule. The streets are well-planned and supported by a complex drainage system, and the entire city seems to have a bizarre focus on sanitation. Where you might expect a seat of government or a religious altar, instead there sits a gigantic communal bath. According to National Geographic, the city’s entire culture may have been constructed around concepts of cleanliness. But we can’t say for sure, any more than we can say why it was suddenly abandoned.
This is a genuine riddle in archaeology. There are no signs of flooding, no signs that a competing city invaded. There is some evidence that climate change disrupted a vital river, but that wouldn’t account for the swiftness with which it was abandoned. All we know is that, around 1900 BC, Mohenjo Daro’s inhabitants left their city, never to return. Why that might be, we’ll probably never know.
5.
Tripura (Ancient India):
In Hindu tradition, the Tripura were three cities - one made of iron, one of silver and one of gold - that sat on Earth, in the sky and in heaven. Populated by corrupt and evil demi-Gods, they were eventually destroyed when Shiva set them alight in a fit of wrath, burning everyone inside. Now it’s likely that this is just another story, a myth that arose separately to the Genesis account of the Cities of the Plain. But isn’t it possible that they and other accounts - such as the ancient Akkadian Poem that describes cities being destroyed in a rain of fire - come from the same, half-forgotten memory: of the morning when a meteor burned high above Ancient Canaan? If it were true, that would make this long-forgotten town the inspiration for some of the world’s greatest and oldest legends. If it were true.
6. Hyperborea (Ancient Greek):
HYPERBOREA was a fabulous realm of eternal spring located in the far north beyond the land of winter. Its people were a blessed, long-lived race free of war, hard toil, and the ravages of old age and disease.
Hyperborea was usually described as a continent-bound land, bordered by the great earth-encircling river Okeanos to the north, and the great peaks of the mythical Rhipaion mountains to the south. Its main river was the Eridanos, which flowed south, drawing its waters directly from the Okean-stream. The shores of this stream were lined by amber-bearing poplar trees and its waters inhabited by flocks of white swans. Blessed with eternal spring, the land producing two crops of grain per year. But most of the country was wild, covered with rich and beautiful forests, "the garden of Apollon."
To the south the realm was guarded by the bitterly cold peaks of the near-impassable Rhipaion mountains. This was the home of Boreas, god of the north wind, whose chill breath brought winter to all the lands to the south--Skythia, Thrake, Istria, Celtica, Italy and Greece. The peaks of the mountains were also the home of Griffins (eagle-lions), and its valleys were inhabited by the fierce, one-eyed Arimaspoi tribe. Directly to the south lay Pterophoros, a desolate, snow-covered land cursed by eternal winter.
Hyperborea was a theocracy ruled by three priests of the god Apollon. These gigantic kings, known as the Boreades, were sons or descendants of the north wind Boreas. Their capital contained a circular temple dedicated to the god where hecatombs of asses were sacrificed in his honour. The musical race also celebrated his divinity with a constant festival music, song and dance. The hymns were joined by the sweet song of circling, white Hyperborean swans.
7. Buyan (Slavic Mythology):
n Slavic mythology, Buyan (Буя́н

is described as a mysterious island in the ocean with the ability to appear and disappear. Three brothers – Northern, Western, and Eastern Winds – live there.
It figures prominently in many famous myths; Koschei the Deathless keeps his soul hidden there, secreted inside a needle placed inside an egg in the mystical oak-tree; other legends call the island the source of all weather, created there and sent forth into the world by the god Perun. It is also mentioned in 'The Tale of Tsar Saltan, of His Son the Renowned and Mighty Bogatyr Prince Gvidon Saltanovich, and of the Beautiful Princess-Swan' (an opera by Nikolai Rimsky-Korsakov) and many other Slavic folktales.
Some scholars interpret Buyan as a sort of Proto-Indo-European Otherworld (see Fortunate Islands). Others assert that Buyan is actually a Slavic name for some real island, most likely Rügen.
That should keep you busy for a day or three

. I'll see what I can dig up (heh, a pun, funny

) on the Naacal in the next few days.