User blog comment:Mr. Youtube/Columbia and Rapture/@comment-159.46.2.61-20130403084216

One thing that also could be possible is: it being 2 different realitys that both columbia and rapture never co exist in the same reality. So let me put it this way in one reality they decided to make a floating city and the other the decided to make it underwater. I think its the most simple theory and the one they will go forward on. Making new amazing citys in different realitys with certain similarities like the powers (plasmids and vigors) and the guars (handyman/big daddys).