Holiday-goers and locals in Thessaloniki spotted what appeared to be ships floating in the air on a sunny day.
The large vessels seemed to drift lazily across the air above the waterline, violating the laws of physics.
But keen observers may notice that the strange sight is in fact a trick of the light, played on the viewer by the inversion of warm and cool air.
A Fata Morgana is a form of mirage caused when rays of light bend as they pass through air layers of different temperatures.
It can be seen on land or at sea, in polar regions, or in deserts.
The phenomenon has occurred in a few parts of Greece, such as the western side of Samothrace.
The mirage is thought to be the source of the legend of the Flying Dutchman, according to Jonathan Eyers’ 2011 book Don’t Shoot the Albatross!: Nautical Myths and Superstitions.
The mirage is not limited to the sea, and can be responsible for many unusual sightings, including mountains that appear to be hovering.
Frata Morgana is the Italian name for Morgan le Fay, the Arthurian sorceress believed to use withcraft to conjure up fairy castles used to lure sailors to their deaths.
Multiple ‘floating ships’ have been photographed and videoed over the years, with boats appearing to hover off the coat of Britain in Cornwall, Devon and Aberdeenshire in once incident.
In another sighting, four ships appeared to hover above the sea off the coast of Cyprus, forming a line just east of the southern city of Limassol.