A team of explorers say they have discovered the ruins of an ancient underwater city off the western coast of Cuba.
Using sonar equipment the researchers found and filmed huge, smooth stone blocks more than 2,000 feet (650 metres) below the sea's surface.
They say they still do not know exactly what these blocks were for, but they will start investigating the site thoroughly in January.
The explorers first spotted the symmetrically organised stones last year with digital scanning equipment.
In July they returned to the spot off the Guanahacabibes Peninsula with a high-tech robot that films underwater.
Older then pyramids
Experts think these formations could have been built 6,000 years ago - that's 1,500 years older than the pyramids of Egypt.
One of the explorers described the underwater scene:
"It's a really wonderful structure which looks like it could have been a large urban centre."