The Quagmire is one of the most difficult of the ciphers used by the American Cryptogram Association (ACA). The Quagmire IV is the hardest of these. See a description of how it works by clicking on the preceding link. It uses three keywords. Many ACA members solve these by hand (paper and pencil), while others have computer programs to help. You can download my Windows 32-bit interactive solver from here if you like: Quag.zip but it is not necessary to solve the cipher. Following is the text of the cipher:
NUOLL FDDFN EWFQP OKGNJ DGGJF BBQFB AXFPT XMFRQ LMGKY BPMDT PLKGP
VKFSF HSODK IDTDS SAMDN ORMWT JJBOP IBOKN DXBMP QQBPV MFRDQ BNUQU
MBNHB NDTTQ QBMHC DRVDC EVMVA RYUGQ NLOWE WBJOK TVTCB PQCRG YNEOH
GAQNR KIOFV QZFDJ FPRVP SPVDS SAMKB MRNWC VYELO IGSFP LJVFG TQBGY
QYQAY PBQDM QBQIX VJSQD CFCWE KAFDT TTSIW CQTLV OSTQS UIMPG QXQWP
VJYPO FTXLU FRQFH NIXNV QVFXH FEQRX FCJ
To assist you in solving here is some additional information. The phrase "ARE SOME OF MY FAVORITES" appears in the text. That's known as a crib. (Note: I recently discovered that my solver required the crib to be entered in lower case, no spaces. I have fixed it to accept upper case, but still without spaces. If you downloaded the earlier version of my solver, I suggest you download it again. The crib, if entered correctly, should be placed uniquely by the program.) The three keys are all ordinary single words and all relate to the subject matter of the text. The text does not relate to geocaching, but is ordinary English. There are no tricks intended, just straight cryptography. If you use my solver, don't click on the Save Solution button as it expects some existing files and will just produce an error. You don't need the text of the solution, just the keywords.
Once you have deciphered the text, enter the three keywords, without spaces, in alphabetical order into certitude to get the actual coordinates
You can validate your puzzle solution with certitude.