Follow in the footsteps of legendary Wind Cave explorer Alvin McDonald by encoding your own initials.

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ZUQ: Alvin McDonald's Initials Encoder uses the same algorithm that cave explorer Alvin McDonald used to come up with his signature initials ZUQ, which he used to identify himself while exploring South Dakota's Wind Cave between 1889 and 1893.

For a long time his algorithm remained a mystery, with the only hint appearing in a post script from a journal entry dated Janurary 1, 1892.

For the meaning of these initials or any other initials used in the pages of this book, inquire of the guide of any of the Celebrated Caverns of America.

Alvin McDonald

Thankfully, the algorithm was eventually discovered and now everyone can enjoy figuring out their own encoded initials.

Learn About Alvin

Alvin Frank McDonald was an early American caver and tour guide at what would become Wind Cave National Park in South Dakota, one of the longest caves in the world, from 1889 to 1893.

From the age of 16 until his death at the age of 20, Alvin discovered and mapped 8 to 10 miles (13 to 16 kilometers) of the cave by candlelight. His exploration and mapping was so extensive and thorough for the time that it was not until 1963, 70 years after Alvin's death, that major new passageways were discovered in Wind Cave.

To learn more about Alvin McDonald and Wind Cave check out some of the following links.


February 2020

  • Updated frontend.
  • Fixed an Safari error. Alexander

October 2019

  • Updated broken link to Alvin McDonald's Diary. Thanks Preston.

December 2018

  • Updated external libraries.

August 2015

  • Switched to HTTPS.

October 2014

  • Initial release of Alvin McDonald's Initials Encoder.


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