Here is my thoughts and summaries to where we are, where we are going and why. It is a bit long winded, but I put a lot of thought into this and tried not to re-hash to many "Omg thar is 2 smoke monster?>? wtflol " comments.. *clears throat*
I will start this by saying, I have always found the island to be "alive." Not in a human or animal sense of it, but more along the lines of plant life. Self Sustaining and can affect what happens within itself, but can never take any physical action.
The NEW Oceanic 815 First off, we have to combine both camps of season 5 beliefs. Why? Because, LOST has always asked us to allow the ability of belief. What Happened, did in fact Happen. BUT, here's the twist... it also succeeded. The plane does in fact land in 2004. Our lovable cast is still on the the island. How can this be? Think back to Hurley and Miles conversation about time travel. Hurley asks *and I am paraphrasing here* "If this already happened why don't I remember it?" They reset that future, but not their own because it was always their present. Confused yet? Don't be! What happened happened. They crashed on that island and nothing will ever change that. However, by them detonating the bomb they prevented that from happening again. Now, I know your saying to yourself "Dude, Ben was shot by Sayid that never changed anything." Jacob said it the best though, It Only Ends Once *ONCE* Everything else is just progress. Small alterations can be made every time without disrupting the process until the end. The characters have been giving us the answers the whole time. So, it will only end once.. and things can change. but for OUR group.. what happened.. it happened. One group will live their lives..... one group... not so much. We will need to see though if On Island or Off Island was the true way.
Then There Were Two In this corner wearing a white shirt and khaki shorts the king of all that is good and true... JACOB! *ahhhhhh fanfare ahhhh* And in the very very black corner wearing very very black clothes the king of all that is evil... um... some dude who looks like Locke!" Obviously, the two major players here. Who and what they are... well who knows really at this point. The tricky part here is assuming Jacob IS the good guy and the other one is bad. The Others live by Jacob's word. However, anytime we have seen them.. they are angry, murdering self-important jerks to put it nicely. Jacob seems like a nice enough dude true, but I mean acting in the interest of good to further evil has always been an available option. The man in black wants to go home. What if HE is Jacobs prisoner and has to kill Jacob in order to finally be free of this "game." The ash that prevents him from going anywhere is further proof of this. This conflict will be the determining factor of where this show ends and how it all actually started. We still need more pieces to see the true puzzle.
The Underworld Back to my first statement. Why is the island underwater? It has been before. There is no other "logical" explanation as to how the Black Rock arrived where it did. Now, we did see the Black Rock sailing towards the island in Jacob's flash back. This here is difficult for me to explain because if I try to go into time loops and probability my tiny whiskey soaked mind would explode. Albeit, the island or part of it was still rising when the ship sailed in and.... because of the "strange properties" and volcanic attributes of the island it rose quickly and consumed the BR. But why then does it go underwater? To heal! Like a tree in winter it recedes in order to gain strength once again. Impossible? Not in Lost... Improbable.. yea :(. The blast caused the island's heart.. this energy source to make it recede. The magnetism is still there we saw it still effect 815, but was submerged and rendered weaker.
There ya have it! If you have any questions or want any further details let me know.