one piece and merman

I was just thinking........since merman actually live under the sea, why don't they just swim right across the grand line to the last island where one piece is hidden?? that make sense don't you think?? they can just walk along the bottom of the sea or swim across, fish don't need direction, they know where they're going....and arlong is a greedy bastard, he should've realised this great idea long ago........

DOn't double post please. U already posted this in here...

http://www.stoptazmo.com/viewtopic.php?t=9732