So Far, No Further

From publisher blurb:

5th Edition Mini-Dungeon for five to six characters of levels 8-10

The party reaches the end of the known world below; divination reveals only basic information like “weal and woe will occur” or shows fungi-filled caverns. Scouts sent ahead disappear.

These chambers were once submerged witnessing countless sacrifices to aboleths in exchange for fulfillment of darksome desires. Millennia passed, the ocean fell and area drained, and the cavern’s last monstrous being died. But the foulness remains, infusing all that grows; the caves abound with slow-rotting waste and illusion-wielding aberrashrooms.