Tell me about your Underdark

[Nomadic]

I now have a question that stems from the responses in this thread; If your setting has no "underdark", why not?

Er, why would we?

It seems like an exotic element that fits well in certain settings, more like flying islands or underwater cities, not something inherently necessary to all fantasy.

For myself, because I'm mostly working with historical fantasy, I try to avoid diverging too much from the real world. I could forsee other worlds--and have had them in the past--where such a conceit is appropriate. But I see those more as the exception.

What he said (well except the historical part... replace that with similar to earth).

[SDragon]

My underdark, unlike so many others, is actually a quite pleasant place. It does have it's fair share of inhabitants, but they usually don't do much harm. Occasionally, they will spread out and explore other areas, but they don't tend to stay in other places for very long. While it is usually a very friendly place, it is unfortunately rare for outsiders to visit. Awhile back, though, there were some outsiders that wanted to hurt my underdark, but ended up leaving much, much more worn down then when they came.


True story.

[Loch Belthadd]

Most of my, as of now unnamed setting takes place underground so the whole setting is the underdark.

[Steerpike]

Why no Underdark?

A natural Underdark - a vastly connected subterranean cave-system - seems implausible.  It might work in certain worlds that have no problem with such implausabilities, and those worlds can be awesome in their own right, but assuming something approaching an earth-like norm for the planet, it's much more likely that a series of discrete cavern networks rather than a continent-spanning network would develop.

An artifical Underdark or an artificial extension to a natural cavern system presupposes an intensely advanced troglodytic civilization with enough resources to devote to the extremely difficult process of tunneling out large areas - Drow or Illithid or Dwarves, etc.  Such a civilzation would have affected lots of other aspects of the world, so not everyone wants to include an artificial Underdark since it necessitates the creation of a civilzation to build that Underdark.

That said, I'm not anti-Underdark in any way - the Underdark is probably my favorite aspect of Faerun.  It does, however, necessitate the inclusion of lots of subterranean civilizations or a certain level of implausability.

[Loch Belthadd]

well mine is a mix. Due to the extreme dangers of the surface of my world almost everything has, over time gone underground. As they moved further down they expanded their caverns, found new ones, and eventually created the connected underdark. Underdark is not the name of the underground area. It's name varies by culture.
Example: Dwarves call the underdark "The Gift of the Gods", which is one word in Dwarven.

[Llum]

Alright, I've only used an Underdark equivalent kinda thing once, in the Calm setting. The Great Caverns are a system of massive caves and interconnecting tunnels under the continent of Otiron. These are inhabited by Dungeon Elves (banished there by the Surface Elves a long time ago).

In the same setting the continent of Skeir was blasted into the sky (its a giant floating continent now). roughly half of its volume is filled with tunnels. Both these tunnels and the Great Caverns are infested by The Hive.

The only other possible thing is in my largest setting, Divergence, the Fourth Divergence is a kind of Hollow Earth. Its basically Earth but its hollow with four inhabitable layers, the surface and three underground layers that vary quite a bit. This is an example of a natural Underdark kinda thing that is plausible (well positing that the Hollow Earth theory is true :P )

[Bill Volk]

I tend to treat the underdark as the uppermost reaches of hell. No natural life exists deep down, just twisting mazes and metaphysical horrors. So basically it's one big dungeon.

[EvilElitest]

I wish i knew cave geography better, i could do so much more with this idea
from
EE

[Polycarp]

An artifical Underdark or an artificial extension to a natural cavern system presupposes an intensely advanced troglodytic civilization with enough resources to devote to the extremely difficult process of tunneling out large areas - Drow or Illithid or Dwarves, etc.  Such a civilzation would have affected lots of other aspects of the world, so not everyone wants to include an artificial Underdark since it necessitates the creation of a civilzation to build that Underdark.

It seems to me that any people with access to magic are going to turn that magic first and foremost to things that actually matter to them - and though warfare is important, especially to adventurers, to most other people this means stuff like making the crops grow, curing disease, turning 1 gold coin into 10 (and then a subsequent spell to deal with inflation), and building things.  If, for whatever reason, your particular folk live underground, coming up with ways to make more space is probably going to be your biggest priority as a society.  Digging a cave the size of a continent?  Yeah, that seems a bit much.  But an underground society whose best minds are able to fly around and throw meteors at each other - and yet doesn't have a phenomenal grasp of earth-moving (and earth-disposal) magic to go with it - really doesn't deserve to be called an underground society.

[Steerpike]

True, Polycarp.  It is going to take them a lot more effort than a corresponding surface society takes to build cities and highways, though.

[Polycarp]

One could well argue that building something like a paved stone road is a pretty complex procedure - dig quarry, cut blocks, move blocks, survey route, level ground, place blocks, and so on - whereas simply digging is not, if all you're after is a rough-cut tunnel.

In the end, however, I imagine it has a lot to do with how your magic system works.  Unless you're going for a situation where "a more advanced civilization made this a long time ago," you'll want to at least roughly match what exists with the capabilities people have to make such things.  A world with rare, subtle, low-power magic with a world-spanning system of artificial catacombs has some explaining to do.

[Nomadic]

Crazy thought here but what if a chain of now extinct volcanoes had been tunneled out so as to connect lava tubes and chambers? Those things can get pretty big and while it wouldn't be world spanning I am sure it could be quite massive. I mean, how awesome would it be to have a civilization living and moving about in a labyrinthine series of these:

[spoiler=big image]

[/spoiler]

[Ghostman]

Of corse, such realism arguments become rather moot when the world in question is literally a giant disc resting on the shell of a giant turtle, while the sun is a flaming chariot driven by a giant dude, and all the twinkling stars in the sky are candles held by winged, flying dudes. You could simply state that the world was created with all those caves below...