My thinking is that the Ancients (or someone) were experimenting with some new kind of energy. Something went horribly wrong and it got out of control. They had the ability to lock it down and not much else, in essence, putting the "cork" in the bottle. This would lend credence to the fact that this might have been a part of Atlantis at one point, destroyed by its own decadence and misuse of advanced tech (I think that's how the myth went). Some would say that the island is in the wrong ocean for it to be Atlantis, but it has already been proven on-screen that the island "moves" as a result of this energy contained within it. This may have been the result of an ancient experiment to be able to provide a reliable means to travel through time and space instantly but failed due to the extraordinary number of variables involved.
So, several millennia later, along comes Dharma and accidentally starts drilling through the cork to try to get at the energy they detected for their own experiments, not knowing that the whole thing was a containment facility to begin with and they were messing with tech they didn't understand. They screw it up and build Swan to keep it contained with the best tech they had available at the time, an Apple ][ computer. That's a bit tongue-in-cheek, but I think that is going to be the gist of tonight's episode.
This is supposed to be a Richard-heavy story and we know he's been around for a long time. He may have been there for the initial "catastrophe" and may be the only living Atlantean left in the world.
They probably won't make it Lemuria, as not as many people are aware of that myth, being supposedly older than Atlantis itself, even though it would be more geographically "correct" (not taking the "moving island" concept into consideration).