It shows a perfect rectangle the size of Wales lying on the bed of the Atlantic Ocean nearly 3 miles down.
A host of criss-crossing lines, looking like a map of a vast metropolis, are enclosed by the boundary.
They seem too vast and organised to be caused naturally.
And last night the possibility of an extraordinary discovery had oceanographers and geophysicists captivated.
The site lies 620 miles off the west coast of Africa near the Canary Islands — a location for Atlantis seemingly suggested by the ancient philosopher Plato.
He believed it was an island civilisation sunk by an earthquake and floods around 9,700BC — nearly 12,000 years ago.
The grid showed up on Google Ocean, a Google Earth extension that uses a combination of satellite images and marine surveys...