The Elemental Realms (EAFW)

The inner planes that surround the world of Athas are somewhat different than those found in other campaign worlds. The elemental and paraelemental planes make up the entire region, and quasielementals are but a small portion of the larger bodies. The quasi-element of lightning, for instance, is incorporated into the paraelemental of rain. Whether this distinction is real or simply perceived that way by the adventurers who travel there is unknown.
Each of the eight elemental and paraelemental planes resembles an area composed almost entirely of the raw material of that plane. Foreign elements often exist in these planes for several reasons. Some material has been left behind as a result of battles or captured elemental foes. Other deposits may have been created by magic, the whims of the creatures that live there, or may have washed over from a neighboring plane.
Between an element and the paraelements it borders, the composition of the land slowly changes from one to the other. Between magma and fire for instance, there are jutting pillars of earth that appear as if the very stones that comprise them are about to melt
Each of the elemental and paraelemental planes is briefly described below, and the DM should use these as guides whenever a PC travels the planes.
On Athas, the plane of earth is a vast desert ridged on all sides by majestic mountains and jagged outcroppings of rock. The land is dotted with tunnels and caverns, and strange rock islands float lazily in place of clouds.
The realm of fire is a reddish land awash in labyrinthine walls of flame. Great gouts of fire shoot randomly from the crimson earth, and the shimmering heat gives everything a hazy, hellish look. Far in the distance, the horizon seems to be made of impassable fires the size of mountains.
Water's plane is a series of sandy islands, drifting through from the Plane of Earth, and surrounded by muddy tides of murky brine. Most of the spirits live beneath the rippling surface, and one may venture anywhere without fear of drowning. Here, a traveler will see little but water and the pillars of sand that form the islands.
The Plane of Air is a vast, seemingly endless expanse of nothing—except air. Dark clouds from the plane of Steam sometimes float through here, and a traveler can leap from cloud to cloud without fear of falling. If he falls, he simply lands on another cloud. The creatures that live here float on fierce breezes, or dwell in secret in the very center of a floating cloud.
The realm of silt bears a striking resemblance to the Sea of Silt on Athas, and some wonder if the similarity is more ominous than anyone imagines.
A traveler in the realm of silt quickly sinks beneath the surface and finds that he can move by swimming, as if he were in the Plane of Water. Visibility, however, is nonexistent, and the creatures that live here seem to sense visitors by other methods. Of all the ethereal planes, silt is one of the most uncomfortable to visit.
The sun's realm is similar to that of air. It is a great sky lined with a carpet of clouds, though no wind dares disturb them. The glorious sun hangs forever in the sky, and its golden rays are actually visible as they shine down upon the brilliant clouds below.
As inhospitable as the realms of sun and silt are, they are nothing compared to the terrible plane of magma. Giant volcanoes surround travelers here, spewing smoking streams of fiery magma over the glowing coals of earth that line this place. Dense clouds of smoke and ash fill the skies, and the spirits that live here dwell in the huge banks of molten earth that roll ponderously over the land.
The sphere of rain is a dreary place. Dark, funnel-shaped clouds cover the sky, pierced only by the jagged lightning bolts that blast the wet mud on the ground into crater size puddles of liquid.