The group rests, then heads downstream on one of the mushroom rafts.  En route, they are attacked by a giant spider, and Mai Ling gets poisoned for what feels like the 87th time.  Bob also gets poisoned, despite his usual hardiness.

With the spider dispatched, the raft continues into a vast underwater lake.  There are two obvious places to land: a beach to the right (which, following their "left wall" theory, the group ignores) and a pier to the right, from which a group of cultists start shooting at ther heroes.  Other arrows fly out of the darkness as well.  Battle is joined, and two cultists slain before the rafts nears the pier and the cultists retreat.  A trio of skeletons also tries to crash the battle, clawing their way up out of the lake, but are swiftly dispatched by William.

Pursuing the cultists, the group runs headlong into a fairly decent-sized enemy force, and a pretty tough battle follows, in which Cora in particular suffers quite a beating.  Eventually however the cultists are slain - including one who tried to surrender.  After the battle, two derro - decadent, evil, mutant dwarves - try to make a break for it.  Why the derro were present is not known, since no-one has speak with dead yet.

The group gleefully loot the dwarves - who are much more wealthy than the cultists - then head on deeper into the complex.  They encounter another cultist guard point, but overcome those enemies as well, after a brisk battle.

Ahead, the tunnel continues onwards ...