Great Delve

The 'Great Delve' is the unofficial Dwarvish name for the enormous and ever-growing network of tunnels, mines and settlements slowly being carved beneath the surface of Eramon by the Dwarves in their relentless search for their promised homeland, D'aleth Kol. Specifically, the Delve refers to those areas of the subterranean world beyond the established cities and colonies of dwarvenkind, at the fringes of that vast and unknowable underworld of caves, lakes and dwellings that others have called the Deep Dark, the Underdelve, or the Underdark. The dwarves valiantly push to explore this lightless world in their sacred pilgrimage, sending expedition after expedition forth at great cost in resources and Dwarven lives...
For this reason, the Great Delve is sometimes termed the "Deep Frontier" or even the "Dwarven Deathmarch" by those critical of its aims and sacrifices.