There was an anomalous underwater pattern in the Atlantic discovered on Google Earth by various sources that was about 50 km x 50 km. The images are reportedly collected by government resources and given to Google for their Google Earth and Google Maps products. The grid pattern of this image looks like a very large, somewhat symmetrical, city. Some have linked this to a possible site for Atlantis since it’s located in the Atlantic and outside the Pillars of Hercules (Strait of Gibraltar).
Skeptics believe that this anomalous pattern is nothing more than ship tracks, but aspects of the lines in the pattern do not meet the criteria for ship tracks.
Ultimately what this anomaly really is is unknown.
The FarSight video here goes into the hypothetical of what this pattern might actually be. Given the lack of underwater exploration of this sight, this is perhaps the best anyone can surmise if indeed these lines are not ship tracks.
http://www.gpofr.com/documents/2012Atlantis.pdf (broken link 2014)