Robert Sarmast makes the case that Atlantis is a large sunken land mass that incorporates modern day Cyprus. He has sent us sonar imagery(1) of underwater structures. You can also view animations(2) related to the sinking of Atlantis.

1. http://archive.coasttocoastam.com/gen/page1578.html?theme=light
2. http://www.discoveryofatlantis.com/animation.htm