When first established, the Deep Kingdom occupied lesser caverns and tunnels under the Eastern Shaar.
The subterranean parts of the Deep Realm, which comprised the majority of it, was located entirely within the Underdark domain of Great Bhaerynden. It could be found in the north east part of that domain, and was mostly placed in the Upperdark. The surface lands and settlements of the Deep Realm included the Great Rift and the lands directly around it. Most surface dwellers never realized that the dwarven nation occupied a far greater territory than they ever expected, just below their feet.