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BYU’s Underground

While BYU is known for its manicured lawns, lush landscapes, and diverse architecture, few are familiar with the complex underground network of tunnels, rooms, and passageways that lie mere feet beneath it all.

At BYU, rumors abound about what lies underneath campus. Whispered stories of students that have plumbed the depths of campus’ underground have intrigued the BYU community for decades. Such stories have become so enmeshed in BYU folklore that it is at times hard to separate fact from fiction.

It has been half-jokingly suggested that the tunnels extend all the way to downtown Salt Lake City, connecting with the underground passages underneath Temple Square.“ If not to Salt Lake, they surely connect to the Provo Temple,” some amateur amateur urban explorers have surmised. Since at least 2002, the popular “100 Hour Board,” “a BYU online forum run by volunteer students who answer any question,” has perpetuated the idea that there are giant blood guzzling “tunnel worms” that live under campus.

While there may not be secret passageways to temples or monsters living underneath BYU, for 25 years there was a hidden nuclear reactor nestled underneath BYU’s South Hill. The 10-watt L77 research reactor was operational from 1967 until being disassembled in 1992. The nuclear lab that had once housed the reactor was later demolished in 2009. The facility was accessible through a tunnel that began under the Maeser Building. Since 1992 that part of the tunnel system has been completely sealed off.

Students that dare to enter the tunnels without permission, do so at great risk. If a student decides to descend into the depths of the BYU tunnel network, he or she potentially faces severe repercussions. If caught, students face a mandatory $300 fine and the possibility of university and/or legal criminal sanctions. While many students who trespass do so for the thrill of discovery, some have used the tunnels for more nefarious purposes. In February 2020, one such offender, a masked nineteen-year-old student, was caught in the BYU Culinary Support Center after hours. He admitted to repeatedly using the subterranean tunnels to steal food from locked university buildings. He was arrested for burglary.

Fines, expulsion from BYU, and legal charges are not the only threats that face tunnel trespassers. The pipes that extend the length of the tunnels carry 400° steam to heat buildings all across campus. An unsuspecting person touching a pipe or encountering a steam leakage could suffer horrific burns. The motion sensors, legal threats, and other deterrents have all been put into place to protect students’ safety. Those who need to enter the tunnels for maintenance must adhere to strict procedures, including using sign-out sheets. If employees fail to return by the scheduled return time they indicated on the sign-out sheet, BYU Heating Center personnel or the police will go looking for the missing individual(s).

When the BYU Heating Plant was constructed in the 1950’s tunnels were dug to more easily and efficiently heat buildings on campus. Gradually, underground piping was replaced by pipes in the much more long-lasting and easier to maintain tunnel housing. Over time the tunnel network has grown, extending as far north as the BYU Laundry and the Missionary Training Center. Today, only an estimated 10% of underground heating pipes are not contained within the tunnel system.

Originating at the Heating Plant, pipes travel to almost every building on campus carrying 400° steam, pressurized at 300psi, to provide heating. There are around 210-220 heat exchangers on campus, allowing for the high pressured steam to be used in campus buildings. Most buildings at BYU have their own heat exchanger in an underground vault. Although less extensive than the network of pipes for heating, the tunnels also house chilled water pipes that help cool buildings during Provo’s hot months. While the primary use of the tunnels is to provide heating and cooling to BYU buildings, they also provide power and internet through fiber optic lines to some buildings.


An entrance to the tunnels
An entrance to the tunnels There are many entrances to BYU”s tunnel system on campus, however students potentially face severe repercussions for entering the tunnels without permission. Source: “An entrance to the tunnels.” Google Maps, Google ,,-111.6503394,3a,64.2y,27.47h,87.23t/data=!3m6!1e1!3m4!1seMsZKXFuFJ16Ep7WbQn2rQ!2e0!7i13312!8i6656.
Notice to trespassers<br />
Notice to trespassers
Students who enter the tunnels uninvited face a mandatory $300 fine and possible university and/or legal consequences. Source: Anonymous BYU Alumnus. Notice to Trespassers.
 Inside the tunnels.
Inside the tunnels. BYU’s extensive network of underground tunnels is used to supply campus buildings with heat, cooling, power, and internet. Source: Image Source: BYU High Temperature Tunnels . Zwick Construction ,



Ryan J. Hallstrom, Brigham Young University, “BYU’s Underground,” Intermountain Histories, accessed June 23, 2024,