The US Navy has been quietly mapping ocean bottoms for decades, since nuclear submarines started going all over the oceans.[1]  The resolution isn&#x27;t all that great, but by now they know where most of the seamounts are.  It&#x27;s a boring job.  Cruise across ocean in a straight line towing a sonar array, return along a parallel track, repeat.<p>But maybe nobody has bothered to do the Great Lakes in detail yet. Not much submarine traffic.<p>[1] <a href="http:&#x2F;&#x2F;oceanexplorer.noaa.gov&#x2F;explorations&#x2F;lewis_clark01&#x2F;background&#x2F;seafloormapping&#x2F;seafloormapping.html" rel="nofollow">http:&#x2F;&#x2F;oceanexplorer.noaa.gov&#x2F;explorations&#x2F;lewis_clark01&#x2F;bac...</a>