A stade (plural stades, or stadia) was a unit of measurement in the ancient world. In Greek, a stadion, in Latin, a stadium. However, the precise modern determination for the length of a stade in relation to Atlantis is problematic.
As Jim Allen points out, since Plato bases his description on earlier reports originating from Egypt, which stade is he using? If he assumes Greek stades, then the Atlantis Plain would be 300 nautical miles wide by 200 nautical miles long. However, Egyptian and Babylonian stades were also in use, and these are different lengths respectively.
|Stade Name||Metric Length (approx.)|
Engels, Donald, 'The Length of Eratosthenes' Stade', American Journal of Philology, Volume 106, Issue 3, pages 298–311, doi: 10.2307/295030, jstor: 295030. The Johns Hopkins University Press, 1985.
Gulbekian, Edward, 'The Origin and Value of the Stadion Unit used by Eratosthenes in the Third Century BC', Archive for History of Exact Sciences, Volume 37, Issue, pages 359–363, 1987.
Walkup, Newlyn (2005). "Eratosthenes and the Mystery of the Stades". The MAA Mathematical Sciences Digital Library.