Elemental Planes
The Elemental Planes are a specific region of the Dungeons & Dragons cosmology. In the Great Wheel, they make up their own significant portion of the Inner Planes. In fact, they're such a prominent percentage of the Inner Planes - with the others being the Astral Plane, Ethereal Plane and the Prime Material - that their Planescape sourcebook was actually called "The Inner Planes".
As their name suggests, the Elemental Planes are the origin point for all of the various forms of elemental matter in the multiverse. Traditionally, this has made them... rather visually uninteresting. The Plane of Fire, for example, is either an infinite 3-dimensional expanse of roaring flames, or else an infinite expanse of ash fields, lava pools and roaring flames beneath a "sky" of heat waves and noxious combustible gasses. The Paraelemental and Quasielemental Planes tend to have somewhat more variety, as their "margin" status gives them distinctive regions - for example, the Plane of Ice is divisible into Core Ice, the Sea of Frozen Lives (Ice/Water), the Stinging Storm (Ice/Salt), the Frigid Void (Ice/Vacuum), the Precipice (Ice/Air), the Shimmering Drifts (Ice/Lightning), and the Fog of Unyielding Frost (Ice/Steam).
Another downside to their elemental nature is that, well, the Elemental Planes are downright hazardous for anything that isn't an elemental of the right type, and sometimes even for things that are. If being roasted in the Plane of Fire or drowned in the Planes of Water and Ooze doesn't interest you, how about visiting the Glowing Dunes (Magma/Radiance), a technically infinite expanse of radioactive dust that will give you incurable and fatal radiation poisoning? This hazardous nature to visit has also led to many DMs finding them less than interesting - even in Planescape, the Elemental Planes are considered the backwater boonies of the Great Wheel, only marginally better than the Prime. This actually led to the decision to do away with the Elemental Planes and replace them with the Elemental Chaos in the World Axis in hopes of creating a more interesting, more survivable, and more plot-generating form for them. 5e linked them to the Prime in a way reminiscent of Exalted.
In their traditional layout, the Elemental Planes consist of six primary planes; Earth, Air, Water, Fire, Positive Energy and Negative Energy. These six planes are then bolstered by the four Paralemental Planes (convergences of two Prime Elemental Planes) and the eight Quasielemental Planes (convergences of the Prime Elemental Planes with the Energy Planes). Despite the occasional bit of idle fan speculation, there has never been any official word on what the "Paraquasielemental Planes", those meeting points of Paraelemental Plane and Energy Plane, would look like.
Planar Topography
Positive Energy Plane |
Air | Negative Energy Plane | ||
Shimmering Drifts | Precipice | Frigid Void | ||
Ice | ||||
Fog of Unyielding Frost | Sea of Frozen Lives | Stinging Storm | ||
Water | ||||
Choking Gale | Bile Sea | Stagnant Sea | ||
Ooze | ||||
Slag Marshes | Muckmire | Oasis of Filth | ||
Earth | ||||
Obsidian Forest | Scorched Wastes | Sands | ||
Magma | ||||
Glowing Dunes | Searing Mists | Chalk Islands | ||
Fire | ||||
Sea of Stars | Scald | Embers | ||
Smoke | ||||
Aurora | Eternal Haze | Gray Way | ||
Air |
Listed in the above table is the topography for the Elemental Planes. Each of them infinite in size, they border on each other via the Border Planes (not an official name) where the plane partially takes on the properties of the one it borders on. This raises an interesting question: are the Elemental Planes a series of infinitely-sized planes that form a series, or are they a single infinitely-sized plane with many different aspects? Whatever the case might be, there are four Elemental Planes and four Paraelemental Planes. They are connected to both each other and the Quasielemental Planes via the Border Planes, which provide the mixture of the properties of the two planes. This does not mean that the planes are less dangerous on those spots: in the worst cases they combine the horrible properties of the two areas or are even more deadly than their parent plane. To see how these planes interact with the Quasielemental Planes, see the Energy Planes page.
Elemental Planes
The big four. Everybody knows these.
Air
A very big expansion of air. You better know how to fly. Gravity here is subjective, and you can alter the direction of "down" with a Wisdom check. If you can change direction fast enough you can use this in order to land safely. This is difficult at first, but you'll either get used to it or suffer up to 20d6 falling damage.
Water
You better be able to breathe water if you get here. Don't forget a way to see underwater, or be able to deal with whirpools, currents, pockets of acidic and diseased water and of course the predators.
Earth
If you want to make your way around here, you better bring a way to dig. Holes grow shut on their own, so you better dig fast. Another issue is the lack of air: outside of pockets of air there's nothing to breathe. Then there's the issues of earthquakes, gas pockets, the lack of a unified gravity, the darkness... it's a poor idea to come to the Plane of Earth without being very well-prepared.
Fire
Lots of fire here. Upon arriving anything that can catch fire does so, and magical items are given a saving roll at a hefty penalty to escape this fate. Stone melts into magma, water vaporizes and metal melts into slag. The higher your natural AC is the more damage you suffer: humans suffer 6d10 damage, and by ever 3 points your AC is lower than 10 you suffer 1d10 less damage all the way down to no damage at AC -8 to -10. At first. Going deeper gets even worse the further you go, culminating in a place with heat so intense it will incinerate anything, even creatures explicitly immune to fire, up to and including creatures with no physical body or creatures which are literally made of fire. Air quality and visibility are obviously not great but those are the least of your worries.
Paraelemental Planes
The meeting grounds between the various Elemental Planes. Air and Water, Water and Earth, Earth and Fire, Fire and Air; they all produce a Paraelemental Plane. Air and Earth as well as Water and Fire don't have one, because those planes don't touch. Listed are also the six main Border Planes: they are the ones touching the Positive, Elemental and Negative planes of one element followed by those three for the other plane.
Ice
Also called the Frostfell.
Moving around you'd swear that this place has an "up" and a "down" as if it were a big icy mountain. Which is kind of true because of the Border Planes: the "summit" reaches towards the Plane of Air while the "base" floats in the Plane of Water like a massive iceberg. But these are just the outer layers of the plane: near the center of the plane it becomes so cold even those immune to cold suffer because of the cold. Here it is so cold even light freezes and it becomes impossible to see, and even speaking or thinking requires a Save VS Petrification. The cold deals 1d6 points of damage per turn, which becomes 1d6 per round if you dress in many layers and stay out of the wind and water. And don't think about digging: passages grow shut in a matter of days. Oh, and there's avalances and sinkholes too. The plane's also got spots of True Cold, where things like concepts and thoughts can freeze solid. If obtained such things can be thawed out and captured to be used in magic or sold for profit.
Shimmering Drifts
Precipice
The boundary between Air and Ice. The safest part of the plane, and indeed the only part most explorers actually visit. Towards the direction of Air, it resembles a howling blizzard, slowly growing weaker as one draws further from the border. Towards the direction of Ice, the infinite ice of the plane breaks to a surface, resembling the arctic lands of any number of Prime worlds.
Frigid Void
The border of Ice and Vacuum. Cold is the only thing that exists in this place, with ice and snow replacing the blackness as you get closer to the Ice side.
Fog of Unyielding Frost
The border between Ice and Steam. The vapor here is super cold, and breathing it will probably freeze your lungs from the inside out.
Sea of Frozen Lives
The border between Water and Ice. The water here is just above freezing, and the closer to Ice you get the more ice chunks start appearing in the ocean until it's just a big chunk of ice with a bunch of streams running through it.
Stinging Storm
The border of Salt and Ice. Acrid, metal-dissolving blizzards of dry ice, desiccating salty winds, and snowdrifts that will dissolve your boots make this a thoroughly unpleasant place to be.
Ooze
Also called the Swamp of Oblivion.
The trash heap of the multiverse, Ooze is made of all sorts of muck, mud, unpleasantness and highly potent acid that can deal up to 1d20 damage per turn with a -4 on your save. Breathing and seeing is difficult here as well. Many powerful realms amongst the planes use the place as a trash heap, including Sigil. If you're willing to pick through the junk, you just might find something of value. Whether or not it's worth it by spending time in the Ooze is another question. One of the more unusual inhabitants of the plane are a group of Gnomes who accidentally ended up in the place digging in via the Plane of Mineral and ended up making a raft to ride the Ooze. Their raft is now some 500' in diameter, and they're doing quite well for themselves.
Choking Gale
Bile Sea
Stagnant Sea
Slag Marshes
Muckmire
Oasis of Filth
Magma
Also called the Fountains of Creation.
Ever played "the floor is lava" as a kid? Good, because here everything is lava. Breathing is difficult, everything catches fire, magma bubbles up, you suffer damage based on your natural AC (but it's only d8 instead of d10), clouds of hot gas mess you up unless you're immune to acid and fire. Lava surfing is generally a bad idea.
Obsidian Forest
Scorched Wastes
Sands
Glowing Dunes
Basically an endless volcanic desert, save for the fact that every grain of sand is so radioactive it makes Chernobyl Reactor 4 look like a sauna! Visiting is generally a terrible idea, though for the more intrepid weapons makers or Dr. Evil-style villains, think of all the nukes you can make!
Searing Mists
Chalk Islands
Smoke
Also called the Great Conflagration.
You better be good at holding your breath, because if you breathe this smoke you'll start taking progressively higher amounts of Con damage over time (and that's if you don't hit a pocket of really poisonous gas). The smoke is also difficult to see through, very hot in certain spots and on occasion even explodes. While it's technically survivable, it's not a very nice place, even when you discount the Smoke being the primary battlefield of the wars between the Djinn and Efreet. In case you want to join them: the Djinn treat their men better while the Efreet pay better. Some of the smokes in Smoke are useful for a variety of magical or recreational purposes, and a few individuals come to the place to harvest and sell them for profit.
Sea of Stars
Scald
Embers
Aurora
Eternal Haze
The border between Air and Smoke. The temperature is more survivable than it is in the Paraelemental plane of Smoke, but it's still hard to breathe unless you're close to the Air side.
Gray Way
Inhabitants
Common inhabitants of the Elemental Planes are:
Surviving on the Elemental Planes
Because of the staggering amount of planes out there, you'll need a variety of gear and spells in order to survive on the Elemental Planes. It's best to gear up for a single plane instead of several at a time, have a backup plan and make sure you know your way out. One of the best ways to prepare is to go to Sigil and buy yourself an Elemental Homucunlous. These come in either the form of a worm or a full suit. The worm (or rather, Breather) can breathe in otherwise hostile gasses and turn them into breathable air, which is useful when going to the Smoke. They can even create air when there is nothing for them to breathe in. The suit proved protection against the negative effects of any single plane, but only in case of that particular plane. So a Homucunlous of Fire won't protect you on the Plane of Magma. As living creatures they can die if they take too much damage, but they can be healed with healing magic (no potions, since they can't drink it). Breathers cost in the 100-500 range and the suits cost in the 300-1000 range, depending on the plane in question.