How does navigation work in One Piece universe?

Question

The navigation devices in the One Piece universe are:

• The compass for the Eastblue, Southblue, Westblue, Northblue
• The Log-Pose for the Grand Line
• The New-World Log-Pose for the New World

Other navigation instruments (in exceptional cases) are:

• The Eternal-Pose for Grandline (always points at the same island)
• The South Birds on Jaya whose bills always point south.
• The Kame-Pose who always points to Mecha

All of these navigation instruments have limitations and disadvantages. The compass, for example, does not work for the Grandline and New World. The Log-Pose can follow only one magnetic wave and takes time to record the next magnetic wave. And the Eternal-Pose works for only one island.

As you can see, navigation in the One Piece universe is very complicated. And this is the point where my question is. Besides the Eleven Supernovas, all other pirates, marines and other ships are free to travel through the whole Grandline and Blues, and to go on any island they want.

In episode 392, Shakuyak explains how hard it is to travel through the Grand Line for the Eleven Supernovas as they tried to get to the Sabaody Archipel. However, the Marines and other pirates commute easily between every island. Do they have an extra expensive Eternal-Pose for every island?

So why is navigation so easy for the Marines and other pirates whereas it is so hard for the Straw Hat crew (as example)?

Answer 1

Navigating is as easy as the goodness of your maps and directional devices. So in general I would suspect navigating to be as difficult for the Strawhats as for any other pirate crew. Pirates usually have the same amount of resources to start with. If anything it should be easier for the Strawhats because Nami has been looking at maps since she was just a child. Although this advantage was never really mentioned in the series and I don't think she was actually able to exploited that knowledge (yet?).

Now you are correct in saying that it is much easier for the Marines to navigate through the world and this makes a lot of sense. The Marines and the World Government have been around for more than 800 years, since the Void Century. Therefore they were able to draw maps of the entire world and would have been able to create many eternal poses for all available islands.

Books with maps are available in local stores or libraries as we can see how Nami's room at Arlong's park was filled with these books. Pirates would be able to obtain these books, but with the WG having much greater funds, I would assume every ship to have such maps available to navigate through the seas. The fact that the Marines travel by map can be seen in chapter 321 when Aokiji takes his map to check the location the Strawhats are about to travel to.

While on the grandline, the Marines use eternal poses to navigate. This can be seen in chapter 128 when Smoker asks for an eternal pose to Alabasta. All they really need to do is contact Headquarters and they will send them an eternal pose, presumably by air similar to the newspaper birds.

With the number of smart scientist the WG would have had over the years, it wouldn't surprise me if the WG would have similar devices for New World. I don't recall there being any mention of such a device just yet though.

Answer 2

Well, part of it is the fact that the Marines won't run into pirate resistance, as they don't get messed up by pirates, not even the strong ones like the Supernovas or the Four Emperors. No one else would think of messing with the Marines if pirates won't (probably).

I'm sure they have many more means of transportation, be it a vessel or navigation instruments, they likely have other technology for easy travel. So I would say yes, they do have other means of travel and even more efficient forms of navigation.

There is also the fact that they know how certain parts of the sea are, and use said knowledge to their benefit and their enemies' disadvantage when traveling.