|This article is about an older version of DF.|
|This article contains massive spoilers. If you do not wish to have your game experience spoiled, do not scroll down!|
 Reaching the Underworld
Upon digging sufficiently deep (usually z-level ~160, but it can vary wildly) you will find huge magma lakes. These are surrounded by semi molten rock, which can not be cleared by digging but seems otherwise stable. Eventually, you will reach a layer which contains nothing but molten rock and little to no possibilities to pass. You can reach the critical layer by digging through solid rock which gets rarer the deeper you dig. There will then be one of two ways through the impassible layer:
Digging through an adamantine vein: Adamantine veins are shaped like vertical tubes and breach through any layer of semi-molten rock, right down into the Underworld. The lower layers of the vein are often hollow and act as a tube, leading straight to your doom. Breaching into the hollow centre of a vein has the same effect as breaching into the Underworld, so beware. You could easily dig around the hollow core provided you knew where it was, but every vein's hollow centre is located a different height - the risk is all part of the fun. Note that adamantine veins always seem to end in mid air, so once you breached the final layer you face a horde of demons which hovers directly below your feet.
Entering a demonic fortress: These fortresses are found once per map tile, as frequent as the old eerie glowing pits. They also go right through to the Underworld, however they are defended by undead creatures and demons on the lower levels. See the full page for more details.
 The Underworld itself
You will receive the above announcement upon piercing the Underworld. One frame later, you will get a second announcement ("Horrifying screams come from the darkness below!") and a massive amount of demons will be spawned - the amount is variable but can fill many pages on the unit screen, so you'd do well to prepare for the worst. It is yet unclear whether the amount of demons is finite; in information exported from the legends screen, the population of demonic species is listed as "unnumbered," a descriptor usually reserved for ants, worms, and other omnipresent vermin.
Demonic invasion doesn't necessarily happen when there are several adamantine pillars present on the map. The demons spawn under only one of those pillars. If the breached pillar is not the pillar where the demons spawn, the demons will be content to float around in the underworld, as opposed to causing oodles of Fun.
The Underworld takes the shape of a large open cavern, seemingly infinitely wide and generally varying between 1 and 4z high, made of slade. Its rough floor slopes up and down, making it possible to walk around and explore should you get an adventurer down there. Far below that are glowing cracks that shine purple light up into the main cavern of the Underworld.
|World Generation (Basic / Advanced / Rejections)|
|Regions - Climate - Surroundings - Map legend|
|Civilizations - Sites ( Cave - Town - Fortress - Ruin ) - Calendar|
|Aquifer - Brook - Island - Tunnel - Volcano - Waterfall|
|Biomes|| Chasm/Caverns - Desert - Forest - Glacier - Grassland - Lake - Mountain|
Murky pool - Ocean - River - Savanna - Shrubland - Tundra - Wetland