ALL BLUE… A legendary area that is supposedly covered with water from all 4 seas with every kind of fish in it and Sanji's dream to find. But where exactly is it? If my theory is correct...
They've already passed it.
Think back to Reverse Mountain.
So, 4 currents from each of the 4 oceans run up the mountain, where they converge at the top.
Technically, All Blue is at this small point. Covered by water from all 4 seas. The fish could either get caught in or swim up the currents to get to it. Seems logical, right? But think for a sec:
How many fish do you think could survive in that? Not too many, me thinks. But if the fish were to be tossed downstream and into the Grand Line…
There would be All Blue. Just as you enter the Grand Line. And, in a sence, it has water from the 4 oceans, because it's flowed down the moutain and into the GL. (Perhaps that could be a bit of a stretch :P)
Of course, I can't forget the unknown.
All Blue could possibly be there too. But we haven't seen that far, so who knows? Oda does, but he obviously won't tell us.
So this is just my idea that I've backed up with fancy pictures and diagrams. Feel free to point and laugh.
(And sorry if someone posted something like this before me. The search button isn't working for me so I couldn't really check….)