Located deep within the Elemental Plane of Earth, the Great Dismal Delve was pocketed with links to a wide array of elemental materials, allowing the Great Khan of the dao to summon allies and resources at will.
In addition to the dao, the Great Dismal Delve housed many kinds of slaves who spent much of their time clearing debris caused by planequakes. The exact number of dao and their slaves inhabiting the Great Dismal Delve was unknown.
- Jeff Grubb, Bruce R. Cordell, David Noonan (September 2001). Manual of the Planes 3rd edition. (Wizards of the Coast), pp. 73–74. ISBN 0-7869-1850-8.