The Caverealm, sometimes also called Underdark or Deepstone, was a vast network of caves and tunnels that lied beneath most of Oshmondu. It could usually be accessed from small tunnels or rifts in mountains and foothills on the surface. This network was distinctly separate from small surface caves, however, and often had only a few small tunnels leading down into the Caverealm proper.

This cave network featured a huge diversity of plants and animals, although not as many and not as location-specific as on the surface. The most common type of plant was fungus. There were also many humanoid races that lived in the Caverealm and built up whole societies, including Khali drow, duergar, and even human states during the Orc Wars. In some surface areas, such as the ice caps and Glacier on Litchy, the Caverealm was closer to the surface and often used as living space by surface races as well.

Geography

The Caverealm was far from equally distributed. It sloped westwards; beginning in the east approximately below Balebu's eastern coast, with a maximal depth of one kilometer, up to the west with a depth of no less than 20 kilometers. Beneath this span laid the Bedwater, the water table, which dropped off as it neared the Infinite Depths.

The actual air spaces (tunnels and caves) were located mostly in the deeper layers, nearer the Bedwater, or somewhat closer to the surface beneath continents. There was generally a "lid" of solid clay and other stones, often quite thick, above the porous inhabited Caverealm; this was notably the case under the entire ocean with very few exceptions, and also beneath continental plates, where there were generally only small caves and very few practicable connections to the underground.

Surface Connections

These are all known connections between the surface and the Caverealm.

Intralu. There were cave networks, inhabited by dwarves, beneath most major mountain ranges and part of the glaciers: Lugsaas, Thar, Galena, Sth. Galena. These had multiple connections to the Caverealm, and one of the places where the Caverealm network essentially reached right up to near the surface level.^[1]

Balebu. The Spine had a few Caverealm links, and some cave networks near the surface as well (see Kurn'Bakal). The Cloud Peaks did not. There were singular connections in the broader continent: notably beneath Holimion and in parts of southern Balebu, as used by raiders during the Orc Wars.^[2]

Bachulu. There were connections in eastern Bachulu.^[2]

Ancetartic. The western polar settlements were known to have passages leading down, notably to Zelina.

Archaen Ocean. No passages except for Conelu.^[2] No Caveralm at all beneath the Luche Archipelago.

Silur. Many passages, eg. used in the Inaendlen Massacre.

Litchy. Passages down from the Ironjaw mountains, and also from the Freezing Peaks and the sub-Glacier networks.

Bao-Mou. Passages around Brizluk.

Balantic. Only two small passages; the sub-polar networks remained largely detached from the near-surface polar settlement.