1. Lost Continents

As the study Lost Continents by L. Sprague de Camp seeks to show, many modern writers speculate about ancient civilizations that dwelled on continents now deluged under sea level. According to de Camp, there is no real scientific evidence for any lost continents whatsoever.

• The most famous lost continent is Atlantis. Atlantis, like Hyperborea and Thule, is ultimately derived from Ancient Greece geographic speculation and memories of the Minoan eruption of the Thera volcano.
• The name of hypothetical vanished continent Mu originated from the first attempted translation of the Madrid Codex, one of only four remaining Maya codices.
• Something similar seems to have happened upon the discovery of the Sanskrit literature by Europeans. Louis Jacolliot claimed to have learned from this literature about a sunken continent called Rutas. This in turn seems to have influenced Madame Blavatsky and her speculations about Lemuria. Speculations about Kumari Kandam by Tamil scholars also seem to be linked to this field. The name Lemuria originated from the hypothesis about a land bridge between India and South Africa.
• Zealandia, a scientifically accepted continent that is now 94% submerged under the Pacific Ocean, surrounding the areas of New Zealand and New Caledonia.

2. Submerged Lands

The Sahul Shelf and the Sunda Shelf during the ice ages and today. The area in between is called "Wallacea". By Maximilian Dörrbecker (Chumwa) - Self made, using this map for the background, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7382691

Although the existence of lost continents in the above sense is mythical (aside from Zealandia), there were many places on earth that were once dry land but submerged after the ice age around 10,000 BCE due to rising sea levels, and possibly were the basis for neolithic and bronze age flood myths. Some others were lost due to coastal erosion or volcanic eruptions. Approximately listed by size, these are:

• Dvārakā, mythical city of Krishna, claimed by some to be found in marine archeology in the Gulf of Khambhat
• Sundaland, the now submerged Sunda Shelf.
• Kerguelen Plateau, a submerged micro-continent which is now 1–2 km below sea level.
• Beringia, connecting Asia and North America.
• Doggerland, the bed of the North Sea, inundated by rising sea level during the Holocene.
• A large island in the Mediterranean Sea, of which Malta is the only part not now submerged.
• Maui Nui, once a large island of the Hawaii archipelago; several major islands represent residual high ground of Maui Nui.
• New Moore Island, an island in the Bay of Bengal submerged in 2010 by rising sea levels.
• Verdronken Land van Reimerswaal, most of this region in The Netherlands vanished in a storm in 1532; the town of Reimerswaal survived as an island into the 17th century; the last bits of land vanished in the early 19th century.
• Strand, an island off the German coast with the town Rungholt, eroded away by storm surges before being washed away by a final flood in 1634.
• Jomsborg and Vineta, legendary cities on the south coast of the Baltic Sea supposed to have been submerged in the Middle Ages.
• Jordsand, once an island off the Danish coast, eroded away by storm surges before being washed away by a final flood between 1998 and 1999.
• Ferdinandea, submerged volcanic island which has appeared at least four times in the past.
• Sarah Ann Island, now submerged guano island, located just north of the equator. Vanished between 1917 and 1932.
• Ravenser Odd, a large 13th-century town on an old sandbank promontory in East Yorkshire, which became an island and then vanished in January 1392.
• Dunwich, the traditional capital of the Kingdom of the East Angles that was lost to the sea by gradual coast erosion and partly by a storm surge in 1286.

3. Mythological Lands

Plato's Atlantis described in Timaeus and Critias. By Athanasius Kircher - https://www.haktanir.org/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=483393

• Atlantis, Plato's utopian paradise
• Lemuria, a mythical lost continent with an ancient Tamil civilization in the Indian or the Pacific Ocean
• Avalon, the mythical lost land or island in Arthurian, Cornish and Welsh legend.
• Buyan, an island with the ability to appear and disappear in Slavic mythology.
• Cantre'r Gwaelod, in Welsh legend, the ancient sunken realm said to have occupied a tract of fertile land lying between Ramsey Island and Bardsey Island in what is now Cardigan Bay to the west of Wales.
• Iram of the Pillars, A reference to a lost city, country or area mentioned in the Qur'an.
• Kitezh, A legendary underwater city located in Russia , populated by spiritual people.
• Llys Helig Welsh legends regarding the local rock formations conceal the palace of Prince Helig ap Glanawg, said to be part of a larger drowned kingdom near Penmaenmawr, Wales.
• Lyonesse in Arthurian literature, it was the home of Tristan and is associated with the Isles of Scilly, Cornwall (an area inundated by the sea c.2500BC), the tale parallels the Welsh and particularly Breton legendary lost lands.
• Númenor an island west of Middle-Earth, east of Valinor in the sea of Belegaer. Was sunken in a great wave sent from Eru Ilúvatar after the men of Númenor sent a great fleet to invade Valinor.^[1]
• Agartha, in the Hollow Earth
• Shangri-La, a fictitious valley in Tibet the idea of which may have been inspired by the myth of Shambhala
• Quivira and Cibola, also known as the Seven Cities of Gold. These were suspected somewhere in America by the Conquistadors.
• El Dorado, mythic city of gold.
• Ys; a mythical drowned city in Brittany, similar to other Celtic lost lands in Welsh and Cornish tradition. Most versions of the legend place the city in the Baie de Douarnenez.

3.1. Phantom Islands

Phantom islands, as opposed to lost lands, are land masses formerly believed by cartographers to exist in the historical age, but to have been discredited as a result of expanding geographic knowledge. Terra Australis is a phantom continent. While a few phantom islands originated from literary works (an example is Ogygia from Homer's Odyssey), most phantom islands are the result of navigational errors.

4. In Literature and Philosophy

The following individuals are known for having written on the subject of lost lands (either as fiction, hypothesis, or supposed fact):

• H.P. Blavatsky
• Edgar Rice Burroughs (The Land That Time Forgot, Tarzan and the Jewels of Opar, At the Earth's Core)
• James Churchward
• Ignatius L. Donnelly
• Arthur Conan Doyle (The Lost World)
• Burak Eldem
• Warren Ellis
• Philip José Farmer
• Geoffrey of Monmouth first mention of Avalon in his Historia Regum Britanniae
• James Gurney (Dinotopia)
• H Rider Haggard
• Robert A. Heinlein (Lost Legacy)
• James Hilton (Lost Horizon)
• Robert E. Howard (Conan the Barbarian)
• Édouard Lalo (Le roi d'Ys)
• H. P. Lovecraft often invoked the names of lost lands of his own invention, a practice that subsequently gave birth to the Cthulhu mythos.
• Plato
• Augustus Le Plongeon
• Zecharia Sitchin
• J. R. R. Tolkien partially based the story of Númenor, referenced in The Lord of the Rings and The Silmarillion, on Atlantis.
• Samael Aun Weor
• Jack Vance (Lyonesse Trilogy)
• Jules Verne used the idea of a partially hollow Earth in his novel A Journey to the Center of the Earth (1864).
• Lost lands figured prominently in the philosophy of the Nazi Thule Society in regards to researchers of the occult and Nazi mysticism such as Karl Maria Wiligut, Heinrich Himmler and Otto Rahn.