One Piece Episode 480

[Endrance]

One Piece recently has many holes like that and you can argue and speculate ten pages about such matters, which people like Darth Ender, UChessmaster or whoever would without a doubt do. But in the end there's really not much to argue. I mean, those episodes been awesome and all, but you can even expect a shonen to get basic stuff like this right. Even if you have to resort to invisible walls, that'd still be better than half of the strong combatants idling the majority of the time for no good reason whatsoever (not showing apparent battles is not an excuse, you have to at least give the viewer a clue why they aren't doing much or what exactly they're doing - I can imagine alot without proper indications, but that doesn't make the plot any better).

But well, be happy with what you got and learn from it. I'm currently into writing a story myself and watching anime like One Piece really already helped me avoiding major mistakes that'd make the whole world concept break apart. One Piece diehards just ignore logical holes like this by default, so better don't try to get into a discussion about such "trivial" matters. You'll be flamed and hated and then ignored.