Square Footage Of Megayachts?

I have been wondering this for quite some time now. How many square feet are some of these yachts? I read that Pangea is 7,000 @ 184 feet long. However, since she is an expedition vessel, she lacks the interior space of the same sized yachts that are the classic types of megayachts. Specifically Octopus and Rising Sun...what do you think the square footage on these are? Thanks.