A branching pipeline bearing dubious water, but doubtlessly leading somewhere critical to the plot...
I have played around with sewers in previous battle maps, but never with a predefined layout and classic, round pipes! These new ones sport bends designed to hide enemies and encourage exploration, all while stomping through thick kelp and other debris. Barnacles and seaweed thrive here because, in my imagination, the tide sometimes sweeps in to replenish them. There is also a section of flowing water to deal with, and a small grove of happy toadstools.
I have experimented with a very dark alternative version this time, designed to look better with pure black fog of war. It's also just a bit more atmospheric, if you're playing in a room dark enough to enjoy the details:

Hope you can find an excuse to send your heroes down into the sewer again! I'd love to hear what sort of encounters (monsters and otherwise) come to your creative minds. Please do share below. :)

Thanks to Patrons like you this map is released under the CC BY-NC 4.0 license.