3D Image: Looking through water and mud

[granfire]

http://now.msn.com/civil-war-shipwreck-seen-in-3-d-sonar-images

Stunning image, though i would like a few explanations as to what I am looking at.
But fascinating: Those circular spots, with the dark center....canon balls?

 

[Sukerkin]

What a fascinating process - well done to the boffins who figured out how to do this :thumbsup:.