From publisher blurb: OPERATION UNFATHOMABLE is an internally-consistent, gonzo funhouse that runs like a subterranean wilderness trek instead of a “down the 10 foot hall and kick in a door” affair. There are random elements aplenty to keep GMs guessing as well as players. No balanced encounters to be found here, but the clever setup allows low level characters to drop into the dungeon “deep end” and still have a chance of making it out alive—if they’re smart and wary. OPERATION UNFATHOMABLE includes: Underworld Phenomena: Novel environmental hazards to challenge explorers like Horizontal Cave Lightning, Whirlwinds of Unbidden Transportation, Sudden Seismic Events, and many more! Fractious Factions: Enter a crossroads of Underworld civilization where combat is only one of the options (and often not always the wisest!) for dealing with its denizens. The PCs can make a temporary truce with Blind Antler Men or forge an unlikely alliance with the minions of Nul the Mindless God! Races, Weirdos and Chaos Godlings Galore: Over two dozen new creatures, from Batwinged Dwarfs to Shaggath Ka the Worm Sultan, malevolent...and even more malevolent! Near-Endless Adventure: Enough NPCs, encounters, and areas to explore to keep a campaign going well beyond the initial scenario.