I think I know how the Island gets submerged. To understand this post you will need to read my previous post on MIB\Genie. I am attaching it here:
The MIB/Smoke Monster is a Genie that is trapped on the Island and is controlled by Jacob. The Genie must do all of Jacob's bidding and cannot harm Jacob or anyone under his protection. I believe that Jacob came to be on this Island a long long long time ago and while there found the Genie and freed it and by doing so became the Genie's master forever, but in realizing it's power, would not allow it to leave the Island and more or less has become it's guardian until someone can figure out a way to kill or neutralize it's power. I think that one of the first things Jacob asked for was eternal life, so Jacob is very old. I think that the only way for the Genie to break its bond with Jacob is to find a way to escape the Island from which it is forever bound. I think that Egyptians put the Genie on the Island under the Temple to imprison it from the rest of the world in both Time and Space. I also think that the Egyptians created the wheel. I also Believe that Ilana is with a group of people that are trying to keep it from being discovered or leaving the Island until a way for it to be destroyed is discovered. I think that Ilana and Bram are descended from the same group of people that brought the A Bomb to the Island to attempt to kill the Genie. I also believe that Organizations controlled by Hanso, Paik, Widmore and others are trying to take possession of the Genie so they can become it's new master and have it do their bidding. I think the DI were there secretly trying to find a scientific way to either control the Genie or destroy it. I think that the Others have to listen to what Jacob says but that they also worship the Genie as a Deity. I think the jest of it will come to fruition in season 6 even if a few of the points are incorrect.
Now on my theory of how I think the Island was submerged: MIB was a man that was turned into a Genie and Jacob had control of him which is why MIB could not harm him or anyone that he had touched due to the rules a Genie must follow. Jacob is trying to find a replacement for himself but is looking for specific qualities in a person before he is confident that no evil will be done with the use of the Genies power. The names on the ceiling are the Candidates to replace Jacob with this important responsibilities. I believe in the end Jack Shepard will replace Jacob and in one final act he will think of something that Jacob never had which is to have the MIB\Genie\Smokey to sink the Island, trapping the Genie underwater in a cave forever and preventing any humans from setting foot on the Island again.