Usually, heroes travel between the two levels through the use of subterranean gates, but they can also use monoliths, or whirlpools. The adventure map of the subterranean level is always the same size as the surface, but usually, a lot of the space is not utilized, containing nothing but a black emptiness. Sometimes, both levels are filled with explorable land, and in a few rare cases, the subterranean level is actually more developed than the surface. The Regicide is a good example of the latter.