I have no doubt that whoever coordinated Flight 815 to fly over the specific spot for entrance to the island, had a spare plane ready to be dumped in the ocean to specifically be found by investigators. It's deep enough where a robot can see a plane, perhaps it's call numbers and bodies inside, but too deep to be salvaged, therefore.. investigation over!
We cannot discount the rich guys in the show, specifically Paik and Widmore. Paik's honor is prob hurt since he wouldn't be able to have grandchildren, his daughters infidelity... same for Widmore. I'm thinking now that whoever this Jacob turns out to be, a wizard or not, he probaby has given more power to these guys than they could afford financially... meaning, he demands sacrifices... in the form of your first born OR others. Widmore sends his hated, almost son-in-law, Paik sends his daughter and her sperm free husband.
If we are to believe that Mrs Hawking knows the future as she's shown with Desmond, perhaps Jacob has allowed her to give information to the rich guys in return for favors....

anyone buying this?