The Mysterious Hanging Boulder fell on the final day of Polar Caves Park’s 2026 season, smashing part of a walkway without causing injuries.
RUMNEY, N.H. — An 80-ton granite boulder that had hung above visitors at Polar Caves Park for more than a century collapsed onto a walking trail, damaging the attraction but leaving no one injured, park officials said.
The Mysterious Hanging Boulder fell Oct. 18, the final day of the park’s 2026 season. The massive rock had been one of the best-known features at the White Mountains attraction since it opened in 1922. Generations of visitors walked directly underneath the formation, where a trail sign warned that most of its weight extended over their heads.
Park officials said nobody was in the boulder’s path when it came down. Images and video recorded after the collapse showed the rock blocking part of the trail and damage to a wooden walkway and railing. Polar Caves said it would use the offseason to evaluate the site and decide what repairs or other steps are needed before visitors return in 2027.
The boulder’s fall ended a 104-year run as a landmark at the privately operated attraction, although the granite formation itself was far older. The caves and giant rocks at Polar Caves were shaped by glacial activity during the last Ice Age. As glaciers moved across what is now New Hampshire, they carried and deposited enormous blocks of granite, leaving passages and caves between them.
A sign near the Hanging Boulder described the rock as weighing 80 tons and resting on three points of contact. It also said about 75% of the boulder extended beyond its support, placing much of the rock directly above the trail. The unusual position helped make it a popular photo stop and one of the park’s most recognizable natural features.
The precise reason the boulder fell has not been established. Park officials did not announce a specific cause. Geologists interviewed by The Boston Globe said long-term erosion, gravity and repeated freezing and thawing could gradually weaken a balanced rock formation. Jan Earle, a geologist who has worked with the U.S. Geological Survey and state parks, said such forces can slowly reduce support until gravity causes a rock to tip.
University of New Hampshire glacial geology professor Joe Licciardi told the Globe that freezing water may also contribute to fractures in rock. Water expands when it freezes, which can widen cracks over repeated seasonal cycles. Those explanations describe possible natural processes, but officials have not said which factors caused the Polar Caves boulder to collapse on Oct. 18.
Polar Caves Park opened in 1922 and features nine granite boulder caves, hiking paths and other outdoor attractions. The park sits in Rumney in New Hampshire’s White Mountains region. Its maze of large rocks and narrow passageways has made the site a longtime destination for families and tourists traveling through the state.
The collapse recalls the loss of another prominent New Hampshire granite landmark. The Old Man of the Mountain, a natural formation resembling a human face on Cannon Mountain, collapsed in May 2003 after years of weathering and geological stress. That formation had become an official state symbol and appeared on New Hampshire license plates and a U.S. commemorative quarter.
Polar Caves officials said visitor and employee safety remains their priority and expressed gratitude that no one was hurt. The park is closed for the offseason while the damaged area is assessed, and officials said they expect to welcome visitors back for the 2027 season. They have not announced the extent of repairs needed around the fallen boulder.
Author note: Last updated October 25, 2026.