Lemuria — The Continent That Was Once a Reasonable Idea
Lemuria began as a legitimate scientific proposal to explain why lemur fossils turn up in both Madagascar and India, was rendered unnecessary by the discovery of continental drift, and then had a long and successful second career as a sunken homeland for spiritually advanced ancients.
Why it was classified
There was nothing to hide, only an obsolete hypothesis that nobody told the mystics about. The zoologist Philip Sclater proposed the land bridge in 1864 as a sober solution to a real biogeographical puzzle, and Ernst Haeckel entertained it as a possible cradle of humanity. Once continental drift was established, and confirmed by seafloor spreading evidence in the 1960s, the puzzle dissolved: India and Madagascar had once been adjacent, as part of Gondwana. No sunken continent required.
Why it matters
By then Helena Blavatsky had incorporated Lemuria into Theosophy as the home of a 'root race,' and later writers added crystal cities, refugees escaping to Mount Shasta in California, and a general link with Atlantis. The occult version outlived the scientific one by more than a century. It is a clean case study in how ideas decay: a testable hypothesis is proposed, is superseded by a better explanation, and the discarded version goes on to a far more comfortable life in which it can never be wrong again.
Where was it, then?
Modern seekers, undeterred by Gondwana, have proposed relocations. The desert theory holds that the Thar Desert on the India-Pakistan border, and by extension the arid belt running west from it, is Lemuria after the water left, with the sand standing in as evidence of a drowning that ran in reverse. The other favourite is the Bimini Road in the Bahamas, a submerged line of limestone blocks off North Bimini that gets assigned to Atlantis on Mondays and Lemuria on Tuesdays, despite sitting in the wrong ocean by roughly half a planet. Both are speculation with no supporting fieldwork, and both quietly ignore the point that Lemuria was originally an Indian Ocean land bridge, not a Caribbean one, and not the Land of Mu, which is a different invented continent entirely. The two get merged anyway, on the grounds that they are both underwater and neither can object.