In ancient stories Fata Morgana (also known as Morgan le Fay) was a fairy enchantress skilled in the art of changing shape. One story says she learned many of her skills from Merlin the Magician and lived in a castle under the sea.

She sometimes made her castle appear up in the air, luring seamen to what they thought was a safe harbor. Her name is therefore given to an optical illusion (or mirage) of solid, well-defined coastal features that appear where there are none. Distant objects are distorted and stretched vertically - or a flat shoreline may appear to have tall cliffs, columns, and pedestals.

Alternating warm and cold layers of air near the ground or water surface cause light to be bent towards the colder, denser air. The result can be a distorted light path and a strange image of a distant object that is, in fact, not there.

Early Arctic explorers often recorded islands or mountain ranges that did not exist - even going so far as to let them block their path (Sir John Ross being one example).