If Raftel is at the end of the Grand Line, why not even a single person tries to get there by going back from the Reverse Mountain?
http://img442.imageshack.us/img442/6191/yibisonepiecemovie9720p.jpg
I guess Oda probably has some reason for this to be impossible or at least much more harder and dangerous than the long way, but why we haven't seen anybody crazy enough to try it? Or why did Marines not trying to pass through Calm Belt near Reverse Mountain to get there with their fancy Sea-King-Proof ships?
If nobody couldn't find the island since Roger, then it's either simply impossible to get there or no one is smart enough to find a shorter way. I will be disappointed if it turns out to be just a normal island, but I hope(actually I'm pretty sure) Oda has some great explanation on that. But still, he should at least have hinted about it.
Any ideas on that?