B2: The Cave of the Unknown

The Cave(s)* of the Unknown area is left for you to use as a place to devise your own cavern complex or dungeon maze.  If you do not wish to undertake this at first, simply DO NOT ALLOW YOUR PLAYERS TO LOCATE IT EVEN IF THEY THOROUGHLY SEARCH THE VERY SPACE IT IS IN. (It was hidden by a magical illusion so as to be undetectable...)

The Keep on the Borderlands

There are as many ideas for "The Cave of the Unknown" as there are DMs who have run module B2 "The Keep on the Borderlands".  Many have shared their maps online, with some having been formally published.

*"Cave" is singular in the Holmes version, and plural in the B/X version, probably as a result of an error introduced while re-typesetting the module

Fan Versions:

My unkeyed map for the Cave of the Unknown.

I've tried my hand at creating maps for the Cave of the Unknown (one version of which is reproduced, above) but have never gotten around to keying any of them.

(These days, I prefer to restock the atmospheric Lost Caverns of Tsojconth, my fan version of which is downloadable here, for an "all Gygax" feel to module B2).

The earliest published version of the Cave of the Unknown appeared in "Keep on the Borderlands: The Expansion" (OSRIC, 2013).

An excellent, fully keyed version was posted by Greg MacKenzie at Project on the Borderlands, here (2014).  Greg later posted four more jaw-dropping levels (2018), here.

Of the other versions posted, I particularly like the one shared by C. Wesley Clough on his WordPress site in 2018, here.

The Caverns of Quasqueton:

Although perhaps not the best fit,* some have substituted the Caverns of Quasqueton from module B1 "In Search of the Unknown" in place of the Cave of the Unknown.

*Rogahn and Zelligar's underground fortress was "far from the nearest settlement, away from traveled routes, and high upon a craggy hill" which is at odds with the nearby Keep and road, (to say nothing of the missing lookout tower)

John Rateliff may have been the first to suggest the idea in print.  The wilderness map in "Return to the Keep on the Borderlands" labels the Cave of the Unknown as "Quasqueton".  Inside, the party finds a 20' x 30' antechamber, with corridors to the left and right:

The left-hand passage has an arrow and the word "QUASQUETON" engraved at eye level only a few feet in; this way once led to the secret fortress of Quasqueton, but the tunnel has completely collapsed; characters can only go this way thirty feet or so before having to turn back.

Return to the Keep on the Borderlands

Following suit, Goodman Games' OAR#1 "Into the Borderlands" (2018) likewise used the Caverns of Quasqueton as the Cave of the Unknown, (although the writers do suggest the possibility of the DM substituting his own dungeon).

BEX-1 Descent into the Caves of the Unknown:

Descent into the Caves of the Unknown (2018) by RC Pinnell

BEX-1 "Descent Into The Caves Of The Unknown" by the prolific Thorkhammer (RC Pinnell) is a free, 8 page treatment of the Cave of the Unknown, designed for 4 to 9 characters, levels 3 to 4.  The adventure includes a fantastic map, and is quite well done.

B2.5 Caves of the Unknown:

Dungeon Module B2.5 "Caves of the Unknown" (2018) by Charley Phipps, Thom Wilson, Mike Badolato

Druvas shared a version of his map for the Cave of the Unknown on Dragonsfoot, back in 2012, here, which later served as the basis for Dungeon Module B2.5 Caves of the Unknown, (NTRPGcon, 2018).

I don't have a copy (it's really hard to come by), but you can check out a review by Bryce Lynch, here, as well as a YouTube review by Glen Halstrom, here.

5eF#15 Cave of the Unknown:

Fifth Edition Fantasy #16 "Cave of the Unknown" (2019) by Michael Curtis

Last, but not least, we have Fifth Edition Fantasy #16: Cave of the Unknown, the most up-to-date of the various incarnations of the Cave of the Unknown.

Designed as a tie-in to OAR#1 "Into The Borderlands".  Michael Curtis is an excellent writer and game designer, and this short adventure is no exception.