This treacherous sewer system and the aboleth’s lair it hides is one of a set of three encounter maps originally created for the D&D adventure That Which Never Sleeps; found in issue #195 of Dungeon Magazine.
Sized at 3375 × 2625 pixels, it's perfect for home printing or screen display. Purchase it now to run the adventure or use it on it's own and spice up your game night.