|This article is about an older version of DF.|
A Volcano is a terrain feature created at worldgen. Embarking to a volcano site is the easiest way to obtain magma, as a volcano has magma exposed to the surface rather than dozens or hundreds of z-levels belowground. The volcano will, unlike in the previous version, be consistently shaped all the way down to the bottom of the map. Digging a channel into a warm surface is not recommended/fun, as your miner will be overrun with the magma before completing the task. Digging a channel beside the warm rock then mining directly into it can safely open a magma flow for redirecting.
Volcanoes are one-embark-tile features, meaning that they can be surrounded by any biome. On the Region embark map, they are represented as a red caret (
^), the same symbol as a weapon trap in-game. On the Local embark map they are represented as two tildes (
≈), the same symbol that represents magma in-game. On a standard world map, there will generally be only a few volcanoes.
Any magma in a volcano that is drained will replenish itself over time. This can make tunneling into the lip of a volcano especially fun. The best way to control volcano magma is to pump it out.
Volcanoes tend to appear in mountainous igneous extrusive biomes, which means you may be hard pressed to find flux, coal or wood. You won't need it for fuel, but you will still need it for steel making. If you don't feel like searching hundreds of worlds for a volcano next to sedimentary stone or in a forest, your best bet may be to breach the first cavern for wood (or make tree farms underground once the caverns are opened up), or trade for wood, processed coke or charcoal.
If you really want a volcano next to a sedimentary layer, you can adjust advanced world generation parameters to maximize your chances: increase the minimum number of volcanoes, increase the X and Y variance of volcanism, and set the terrain mesh weights for volcanism to use only the lowest and highest ranges.