Malheur Cave is a lava tube cave located in Harney County, Oregon, approximately east of Crane Hot Springs and east of Burns, Oregon. The cave is privately owned by the Robert Burns Masonic Lodge No. 97 and is notable for functioning as an underground meeting hall for Freemasonry since 1938.
The cave contains an underground lake at its lower end; the United States Geological Survey (USGS) monitors the water level under the designation "Malheur Cave Lake." While historically open to visitors, the cave was closed to the general public in 2019 due to vandalism. It has subsequently become a subject of internet urban legends and conspiracy theories.
Malheur Cave is a classic lava tube extending approximately from the entrance to the rear termination. The entrance is relatively low, but the interior opens into spacious chambers with ceiling heights varying from near the mouth to approximately further inside.
The tube terminates at an underground lake. The water level fluctuates significantly based on seasonal precipitation and the local water table; during high water stands, the lake can extend to within of the entrance. The USGS maintains a water quality and level monitoring site for the subterranean body of water.
Unique among Oregon caves, the interior has been modified to function as a meeting hall. The floor is paved with asphalt in sections, and stadium-style bleachers and a Masonic altar have been installed to facilitate large gatherings.
Long before the arrival of settlers, the cave was known to the Northern Paiute people. It features in regional oral traditions and creation narratives. According to the Oregon Natural Desert Association and published oral histories, the cave is described as an "underworld" or origin place associated with the subterranean water. In the book Legends of the Northern Paiute: As Told by Wilson Wewa, the site plays a role in the tribe's traditional cosmology.
The Robert Burns Lodge No. 97 purchased the cave and the surrounding of land to use as an outdoor (though subterranean) meeting venue. On October 1, 1938, the lodge held its first official meeting inside the tube under a special dispensation. The meeting was illuminated by gas lanterns, and a Master Mason degree was conferred.
The event was conceived by lodge members Ulysses S. Hackney and Charles W. Loggan. It became an annual tradition known as the "Malheur Cave Event," drawing Masons from across the Pacific Northwest. In Masonic circles, it is often cited alongside other caves used for ritual purposes, such as Mammoth Cave and Carlsbad Caverns.
For many years, the cave was accessible to the public when not in use by the Lodge. However, in October 2019, the owners closed access to the general public. Local reporting by the Burns Times-Herald cited "vandalism, trash, graffiti," and damage to the interior seating as the primary reasons for the closure. The report noted that unauthorized parties and safety concerns regarding the uneven terrain also contributed to the decision.
Due to its remote location, underground setting, and exclusive use by Freemasons, Malheur Cave has become a subject of modern folklore and internet conspiracy theories. Various blogs and social media users have circulated unsubstantiated claims portraying the site as a "door to Hell," a location for "satanic" rituals, or part of a clandestine government tunnel network.
A 2019 article by Business Insider regarding conspiracy theories in the United States highlighted the cave, noting that while the rumors are prevalent online, the documented reality is that it serves as a venue for fraternal meetings. The owners maintain a public website explaining the history and use of the cave to counter these rumors.