Editing Planescape (section)

=====The Paraelemental planes=====
If you wish to pass directly from one elemental planes to another, you must pass through the intersections between said planes.  These intersections are semi-planes of material that is a mixture of the neighboring elements. 
The paraelemental planes are:
* '''Smoke''', between Air and Fire
* '''Ice''', between Air and Water
* '''Magma''', between Earth and Fire
* '''Ooze''', between Earth and Water

There are no paraelemental planes between Air and Earth, nor Fire and Water -- unlike many Inner Planes, Air is not adjacent to Earth, nor is Fire adjacent to Water, you would need to pass through the Prime or three other Elemental planes to go from one to the other.  This also holds true for each of the Paraelemental planes.  The paraelemental planes have their own simple life-forms, and unique to them are four races of imps known as "mephits" that hopelessly aspire to be Lords of these bargain-basement elemental planes.  That is not to say however, that they lack princes of elemental good or evil, they do, but they're not that well known, except for Cryonax, who is the Prince of Evil Ice Creatures.

A side-effect of their nature as border-realms between two planes is that all Paraelemental Planes are divided into seven distinct segments, based on their proximity to one of their neighboring planes. For example, the Paraelemental Plane of Ice is divided into Core Ice (the center of the Plane), the Precipice (the surface of ice, lashed by eternal blizzards, bordering Air), the Frigid Void (empty, freezing space, bordering Vacuum), and the Stinging Storm (lashing, salt-laced hailstorms, bordering Salt) on the "top" of the plane, and the Sea of Frozen Lives (freezing cold ocean buried under the Core Ice, bordering Water), the Shimmering Drifts (mind-wiping dazzling drifts of ice crystals, bordering Lightning), and the Fog of Unyielding Frost (churning, super-chilled mists, bordering Steam) on the "bottom" of the plane.

These border regions are usually even nastier than the core region. For example, the Glowing Dunes, the border realms between Magma and Radiance, are essentially a technically infinite desert of ''pulverized radioactive ore'', glowing with atomic energy. And it's explicitly spelled out that there's no known cure, even magical, for the radiation poisoning that afflicts anyone stupid enough to come here.

With shit like this, you can kind of see why the Inner Planes are so disregarded both inside the setting and out.