The Renfall Underground is a massive subterranean cave system in the continent of Renfall. Many explorers and experts theorize that one may be able to travel from one corner of the continent to another, assuming one knew their way around. They theorize, because doing such a thing would be an extremely dangerous feat. Aberrations such as beholders, aboleths, and mind flayers inhabit various sections of the underground. The Drow also make residence in these dark caverns.