Even with today’s GPS guidance systems, it is highly unlikely that these lines were from boat mapping....they are about 100 miles long, perfectly parallel and perpendicular for the most part.
Over the extensive time it would take to map lines of this length, repetitiously, due to vagueuries of weather, winds, currents, etc. would prohibit the precision of these lines. IMHO.
I wholly agree that they are Atlantis is highly unlikely due to the depth and relationship with the consistency with surrounding depth.
What they are, God only knows......