Experts and Scholars on Interplanar Travel- I Need Help Understanding

[GladiusVCreed]

Okay, so just recently I've gotten into the different planes of existence and I understand most of them but what I don't understand is the Elemental Planes. My understanding is that they are all kind of the same plane, but on that plane there are 4 major regions, 4 more paraplanes and 8 more quasiplanes. All of that sounds good..
I drew out the Great Wheel cosmology, and I realized something. On the Wheel, there seem to be "pathways" connecting the Upper planes, and a separate one connecting the Lower Planes. The two Neutral ones (Mechanus and Limbo) aren't connected via these ones. All those pathways, however, connect to what seems to be the Elemental Plane. Does this mean that in order to get to Mechanus from Mount Celestia, I'd have to travel through the Astral Plane into the Elemental, back into through the Astral and finally arrive in Mechanus?
Thanks guys!

[ClintACK]

The Inner Planes (Elemental, Ethereal, and such) and the Outer Planes (Astral and all the Heavens, Hells and such) aren't usually connected.

Depending on the map you're looking at, perhaps the middle bit is Concordant Opposition (the "Neutral" Outer Plane at the hub of the Great Wheel -- Sigil is at the center of this plane). There are supposed to be portals from the top layers of all the Outer Planes to Concordant Opposition -- with "portal towns" around each of the portals. And then a thousand mile trek to get to the next nearest portal.

Or it might be the Prime Material Plane (the real world) -- with the Astral Plane linking it. It all depends on the image you're looking at. And the edition it comes from. :)

Do the "pathways" look like rivers? There was a version in which you could navigate between all the lower planes on the River Styx and the upper planes on a similar good-aligned river of holy water.

[Falcon X]

First off, it depends on which edition you are using. Since you say "Great Wheel" I'm going to assume you are drawing from Planescape/2e. Good choice!
Also, if you follow Planescape philosophy, you should know that everything you and I discuss here is theory. We don't ACTUALLY know the full nature of the planes.

Overall structure: It's kind've difficult to define. It has concepts that the human mind can't fully comprehend such as "How can there be multiple infinite planes in existence" and "If the fire elemental plane is infinite, how does it have borders?" The diagram we have of the Great Wheel is merely the best approximation we have of how they interact together.
A few notes:
1. The inner planes are NOT all one plane (in the Great Wheel). By 5e, they have all merged into the elemental chaos, but not in the diagram you are looking at. Each of the 18 inner planes is considered a separate, infinite plane of existence.
- However, despite this infinite nature, it is possible to physically travel from one Inner Plane to another without a portal. However, a much better way to travel is through the Ethereal Plane.
2. The "pathways" are not pathways. They are just the artist's markings showing how the planes connect to one another.
-In order to get from Mechanus to Mount Celestia, you would need to find a portal.
- You could argue that you must go to the Astral Plane because it lies between all planes. However, there is no D&D cosmology at present that would take you through the Elemental Planes to get between the Outer Planes. (5e Cosmology comes closest because the Elemental Chaos is physically tied to the Abyss.)

The Inner and Outer Planes can be considered on opposite sides of the universe. You must travel through the Astral to get to the Outer Planes from the Prime Material. There are no other connections.
Likewise, the Inner Planes are more directly connected to the Prime Material plane through the Ethereal Plane. You must also go through the Astral Plane to get from the Inner Planes to the Outer Planes.

[Joe the Rat]

There's some variation on the elemental planes. Sometimes they are described as separate realities, with demi- and para- planes being "regions of overlapping theme." You may or may not be able to travel from one to the next directly. But it sounds a bit like you are using an inner, elemental wheel and outer.. .er, outer wheel.

If the positive and negative planes are wrapped around the outer planes, welcome to 5th edition! They're sort of... not elements. they don't really touch the outer planes, except thematically. the middle layers are ambivalent about charge.

Prime Material is the center - it connects to both inner and outer planes via the transitive (ethereal and astral) planes. 3-dimensionally, think of it as Astral projecting upward, Ethereal downward. 4-dimensionally, the astral plane is Zorth from the rest.

[ruy343]

I feel the need to point out here that, although there are great resources for suggestions regarding how the planes work, you get to decide exactly how they work. Coming up with a unique system for things is up to you, and it helps to prevent metagaming, and allows for interesting plot twists as they learn about your system.

That said, the previous posters have given some solid interpretations of how the planes work.