User blog:Ossyria/Grand Line Travel to Blue Seas

Okay so we know how pretty much anyone in the Blue Seas could get to the Grand Line through Reverse Mountain but how would pirates, without going through the Calm Belts or whatever, get back to the Blue Seas? Is there some sort of secret passage that we don't know about? And I'm wondering, is it harder to get back to the North and West Blue seas because based on what I've seen from various fan maps or otherwise, these two seas are on the New World side? So... thoughts?