The Underground River

From the Introduction:

The purpose of this supplement is to add flavor to your game world. It has been intentionally been designed to be generic enough that it can be easily dropped into many different situations. To use this product simply include the location as part of your ongoing game, as part of a dungeon you design, attached to an existing module, or even by itself as a small scale dungeon crawl.

A dusty dungeon hallway has been gently sloping down for 1000 FT, ending in a wide stone stair leading downward. The stairs are covered in slippery green lichens (avoid falling on 1d20 roll GTET [27-Agility]) and lead down 40 vertical FT. The babbling sound of running water is softly heard, along with the faint smell of water.