This material was originally published as two seperate modules, D1 (DESCENT INTO THE DEPTHS OF THE EARTH) and D2 (SHRINE OF THE KUO-TOA). Contained herein are referee notes, background information, maps, and exploration keys intended for use with the ADVANCED DUNGEONS & DRAGONS rules. The module can be used alone or as a part of an extended adventure that begins with Dungeon Module G-1-2-3 (AGAINST THE GIANTS) and continues with modules D3 (THE VAULT OF THE DROW) and Q1 (QUEEN OF THE DEMONWEB PITS).