Muspelheim was formed by similar earthbergs to those that constituted the first layer, Ysgard, but they were inverted with respect to those. In Muspelheim, the fire-lit side faced up, so most of the terrain in the entire layer was dominated by fire and was quite inhospitable to visitors. In many ways, it was very similar to some regions of the Elemental Plane of Fire, which was connected to the layer via numerous portals.
- Muspelheim, realm of Surtr. It contained some of the few arable lands of the entire layer, which were used to grow fireweed, verdobba, and a type of edible black wood.
- Jeff Grubb (April 1987). “Plane Speaking: Tuning in to the Outer Planes”. In Roger E. Moore ed. Dragon #120 (TSR, Inc.), pp. 42–43.
- Wolfgang Baur and Lester Smith (1994-07-01). “The Book of Chaos”. In Michele Carter ed. Planes of Chaos (TSR, Inc), pp. 123–125. ISBN 1560768746.
- Jeff Grubb, Bruce R. Cordell, David Noonan (September 2001). Manual of the Planes 3rd edition. (Wizards of the Coast), pp. 90–92. ISBN 0-7869-1850-8.