That's an outline of the topography of "Zealandia,” a huge island or small continent that mostly sank underneath the water level some 60 million years ago. Stories about Zealandia were trending last week, for some reason. But not being a geologist, and being an historian, it got me thinking instead about some famous lands throughout history that didn't just cease to exist, they never existed.
Invented sometime before 360BC, Atlantis is the grand-daddy of all mythical lost worlds. Atlantis started out as a pretty minor part in one of the Greek philosopher Plato's writings. It was just a place he made up to use in an example of how great the ancient Athenian state was. Atlantis was a made-up boogeyman, representing a government that was the exact opposite of Plato's philosophical ideal. At the end of the story, after the Athenians beat the Atlanteans in war, Atlantis sinks into the sea to avoid uncomfortable questions about where it is now.
But even in ancient times, some people took it seriously, and assumed it was a real place. This has persisted all the way to the modern age, where ridiculous people speculate on maps of where it might have been, new-agers imagine it was the source of ancient wisdom, and the History Channel connects it to "Aliens"!
Lyonesse was the kingdom south of modern-day Cornwall, the legendary locale of the adventures of Sir Tristan, a mythical knight later incorporated into the Arthurian legends. Tristan was the son of the king of Lyonesse, and after Tristan's tragic death the whole kingdom sinks into the sea.
Only "Lyonesse" never existed; it was only created because of what amounts to a translation typo. In the French versions of the the story, the Latin name "Lodonesia" became "Leonois," which was then translated into "Lyonesse." But Lodonesia was actually a real place: Lothian, which isn't a lost land south of Cornwall. It's a very not-lost area in Scotland.
3. Hy Brasil
Ah Brazil, land of frozen seas, mist-shrouded days, harsh rocky terrain and crazy Irish monsters. Wait, that's not right! Or at least, not anymore. But before the nation of Brazil existed, there was a place called Hy Brasil. It was shown on maps for centuries (the earliest was 1325). It was a strange magical island covered in mists, in the sea west of Ireland. It was full of fairies and only appeared once every seven years. Various sailors reported seeing it. It was called Brasil because it was said to be populated by the descendants of the Irish Braseal clan. People kept searching for it as late as the 19th century.
Lemuria has become another favorite lost-continent of the new-age crowd, theorizing that it was the place of some ancient civilization with UFO-supertech and psychic crystal powers. But it started as a flawed scientific theory.
When common lemur-ancestor fossils were found in the southern tip of India and the island of Madagascar in the 1860s, some scientists theorized that there might once have been a continent that sunk into the ocean connecting the two; Madagascar and Sri Lanka were what was left of that great continent, and Lemuria linked to India via a land-bridge.
This was a way to try to explain common fossils over such vast distances, but it was only because back then no one knew about plate tectonics, and that continents actually move over time. After that was discovered, Lemuria wasn't needed anymore by scientists, and got taken up by spiritual kooks instead.
Mu, not to be mistaken with Lemuria above, was another 19th century continent invented by a flawed theory. In this case, trash archaeology. An amateur French Archaeologist who went to see the Mayan pyramids (at that time Mayan history was still mostly a mystery to scholars) theorized that there may have been some great ancient continent, the survivors of which founded both the Mayan and Egyptian civilizations. (Get it? Because both have pyramids!)
At the time it wasn't clear that those two civilizations, and their pyramids, were thousands of years apart in age and weren't built at the same time. He took the name "mu" from a mistranslation of a Mayan text.
Later on, when the theory was already discredited by historians, the Theosophists and other new-agers took it up, making up stories about an ancient race of super-spiritual Caucasians who were responsible for all those advanced civilizations (Egypt, India, the Maya) that just seemed way too impressive to have been done by darker-skinned people. Yes, new-agers used to be super-racist.
The made-up land of Thule was briefly mentioned in some Greek texts, as an Island near the edge of the world, about six days sailing distance north from Britain. "Ultima Thule" was meant to just mean the farthest place in the world, and even in ancient times some scholars rejected its existence as an error.
In ancient history Thule was described as being inhabited by blue-painted savages (confusing them with the ancient Picts of northern Scotland). But in the 19th and 20th centuries, the myth of Thule came back into popularity... among Nazis. They imagined Thule to be the ancient homeland of the Aryan people, a super-advanced Empire of perfect Nazi Supermen. It became a big part of the occult mythology of the Third Reich. Even other fascists like Mussolini used to laugh at them about this, after all, he at least had a REAL ancient Empire to rip off (the Romans). The poor Nazis had to make one up because their ancestors were all bearded savages.